Repository: ISCASTEAM/Algorithm
Branch: master
Commit: 04713061fd8b
Files: 49
Total size: 57.9 KB

Directory structure:
gitextract_kuuyxp0g/

├── 1_Fundamental/
│   ├── README.md
│   └── UnionFind.h
├── 2_Sorting/
│   ├── HeapSort.h
│   ├── Heapsort_test.cpp
│   ├── Insertion.h
│   ├── Insertion_test.cpp
│   ├── Quick3way.h
│   ├── Quick3way_test.cpp
│   └── README.md
├── 3_Searching/
│   ├── BinarySearchTree.h
│   ├── BinarySearchTree_test.cpp
│   ├── README.md
│   ├── RedBlackTree.h
│   └── RedBlackTree_test.cpp
├── 4_Graphs/
│   ├── BFSPath.h
│   ├── BellmanFordSP.h
│   ├── DFSCC.h
│   ├── DFSDirectedCycle.h
│   ├── DFSTopo.h
│   ├── DiEdge.h
│   ├── Digraph.h
│   ├── DijkstraSP.h
│   ├── DirectedGraph_test.cpp
│   ├── Edge.h
│   ├── EdgeWeightedDigraph.h
│   ├── EdgeWeightedGraph.h
│   ├── Graph.h
│   ├── KruskalMST.h
│   ├── LazyPrimMST.h
│   ├── MinTree_test.cpp
│   ├── PrimMST.h
│   ├── README.md
│   ├── ShortestPath_test.cpp
│   ├── TopoLongestPath.h
│   ├── UndirectedGraph_test.cpp
│   └── UnionFind.h
├── 5_Strings/
│   ├── Huffman.h
│   ├── Huffman_test.cpp
│   ├── Quick3String.h
│   ├── Quick3String_test.cpp
│   └── README.md
├── 6_Context/
│   ├── FlowEdge.h
│   ├── FlowFordFulkerson.h
│   ├── FlowNetwork.h
│   ├── README.md
│   ├── SuffixArray.h
│   └── SuffixArray_test.cpp
├── README.md
└── func.h

================================================
FILE CONTENTS
================================================

================================================
FILE: 1_Fundamental/README.md
================================================
代码链接:
xxxxxxxxx
  
# 1.binary search   
url get data练习  
edu.princeton.cs.algs4 普林斯顿算法 jar包   
  
# 2.dataStruct   
queue stack bag  链表实现   
  
# 3.Union Find  
连通集的查找   
API: union find connected  
key: 辅助数组id   
>Quick find   
id[] 相同集合的元素,id[]相同   
   
>Quick union  
id[] 当前元素的root节点序号  
  
>Weighted QuickUnion  
union操作加入size判断  使得较小的子树root指向较大的子树root
小树加到大树上 避免origin quick union depth的过深   

代码不在这里加了   一定要掌握   


``` java
//TODO iterator()方法返回一个实现hasnext() 和 next()方法的迭代器

//first是自己定义的node类型 含有item和next结构

public Iterator<Item> iterator()  {
    return new ListIterator<Item>(first);
}

// an iterator, doesn't implement remove() since it's optional
private class ListIterator<Item> implements Iterator<Item> {
    private Node<Item> current;

    public ListIterator(Node<Item> first) {
        current = first;
    }

    public boolean hasNext()  { return current != null;                     }
    public void remove()      { throw new UnsupportedOperationException();  }

    public Item next() {
        if (!hasNext()) throw new NoSuchElementException();
        Item item = current.item;
        current = current.next;
        return item;
    }
}
```


================================================
FILE: 1_Fundamental/UnionFind.h
================================================
#ifndef UNIONFIND_H_INCLUDED
#define UNIONFIND_H_INCLUDED
#include"func.h"
/*
实现weighted union find
小树加入大树 从而减少树的高度
*/

class UnionFind{
private:
    vector<int> parent;
    vector<int> sz;
    int unionCount;
public:
    UnionFind(int vertexNum)
    :unionCount(vertexNum){
        parent.resize(vertexNum);
        sz.resize(vertexNum,1);
        for(int i=0;i<vertexNum;i++)
            parent[i]=i;
    }
    int getUnionNum(){return unionCount;}

    //API= find,union,connected
    bool connected(int v,int w){
        return findRoot(v) == findRoot(w);
    }
    int findRoot(int p){
        while(p != parent[p])
            p=parent[p];
        return p;
    }
    void unionV(int v,int w){
        int i=findRoot(v);
        int j=findRoot(w);
        if(i==j) return;
        if(sz[i]<sz[j]){parent[i]=j; sz[j]+=sz[i];}
        else{parent[j]=i; sz[i]+=sz[j];}
        unionCount--;
    }
};

#endif // UNIONFIND_H_INCLUDED


================================================
FILE: 2_Sorting/HeapSort.h
================================================
#ifndef HEAPSORT_H_INCLUDED
#define HEAPSORT_H_INCLUDED
#include"func.h"

/*
堆排序
1.构建有序堆(最大堆)
2.不断取出maxVal,在重新有序化即可
3.直到堆中不存在新元素

note:有序化API
swim 上浮
sink 下沉
*/

//e.g.   1....n序号的数组进行排序
class HeapSort{
public:
    static void hsort(vector<int>& nums){
        int n = nums.size();
        for(int k=n/2;k>=1;k--)
            sink(nums,k,n);
        while(n>1){
            swap(nums,1,n--);        //最大值放在数组后面保存
            sink(nums,1,n);
        }
    }
private:
    //父节点k 不断下沉  直到k大于两个子节点
    static void sink(vector<int>& nums,int k,int n){
        while(2*k<=n){
            //k的子节点2k 2k+1中val较大值为j
            int j=2*k;
            if(j<n && less(nums,j,j+1)) j++;

            if(!less(nums,k,j))
                break;
            swap(nums,k,j);
            k=j;
        }
    }

    //helper function
    //由于数组由0开始作为需要标记
    static void swap(vector<int>&nums,int i,int j){
        int tmp = nums[i-1];
        nums[i-1]=nums[j-1];
        nums[j-1]=tmp;
    }
    static bool less(vector<int>&nums,int i,int j){
        return nums[i-1]<nums[j-1];
    }
};


#endif // HEAPSORT_H_INCLUDED


================================================
FILE: 2_Sorting/Heapsort_test.cpp
================================================
#include"HeapSort.h"
/*
堆排序
1.构建有序堆(最大堆)
2.不断取出maxVal,在重新有序化即可
3.直到堆中不存在新元素

note:有序化API
swim 上浮
sink 下沉
*/
int main(){
    vector<int> test={5,4,4,4,44,-1,2,7};
    HeapSort::hsort(test);
    for(auto i:test)
        cout<<i<<" "<<endl;
}


================================================
FILE: 2_Sorting/Insertion.h
================================================
#ifndef INSERTION_H_INCLUDED
#define INSERTION_H_INCLUDED
#include"func.h"
class Insertion{
    //class 默认private
public:
    static void insort(vector<int>& nums){
        int len = nums.size();
        for(int i=1;i<len;i++){
            for(int j=i; j>0&&nums[j]<nums[j-1]; j--)
                std::swap(nums[j],nums[j-1]);
        }
    }
};


#endif // INSERTION_H_INCLUDED


================================================
FILE: 2_Sorting/Insertion_test.cpp
================================================
#include"Insertion.h"

int main(){
    vector<int> test={5,4,-1,2,7};
    Insertion::insort(test);
    for(auto i:test)
        cout<<i<<" "<<endl;
}


================================================
FILE: 2_Sorting/Quick3way.h
================================================
#ifndef QUICK3WAY_H_INCLUDED
#define QUICK3WAY_H_INCLUDED
#include"func.h"
/*
三向快速排序
每次递归将 小数组首元素相同的元素放在相邻位置

优点:
对于大量重复的元素的数组排序 优于传统快排
*/

class Quick3way{
public:
    static void q3sort(vector<int>& nums){
        q3sort(nums,0,(int)nums.size()-1);
    }
    static void q3sort(vector<int>& nums,int lo, int hi){
        if(hi<lo) return;
        int lt=lo,gt=hi,i=lo+1;
        int v=nums[lo];

        while(i<=gt){
            if(nums[i]<v)   std::swap(nums[lt++],nums[i++]);
            else if(nums[i]>v) std::swap(nums[i],nums[gt--]);
            else i++;
        }
        //得到  nums[lo..lt-1] < v=nums[lt..gt] < nums[gt+1...hi]
        q3sort(nums,lo,lt-1);
        q3sort(nums,gt+1,hi);
    }
};


#endif // QUICK3WAY_H_INCLUDED


================================================
FILE: 2_Sorting/Quick3way_test.cpp
================================================
#include"Quick3way.h"

int main(){
    vector<int> test={5,4,4,4,44,-1,2,7};
    Quick3way::q3sort(test);
    for(auto i:test)
        cout<<i<<" "<<endl;
}


================================================
FILE: 2_Sorting/README.md
================================================
代码链接:   
https://github.com/ISCASTEAM/Algorithm   

# 1.Elementray Sorts  
> Select sort P156  
key:选择第i小的元素放入a[i]位置  
note:运行时间和输入顺序无关  
   
>Insertion sort P157  
key:当前索引左边的所有元素是有序的,但是最终位置尚不确定  
note:运行时间和输入顺序相关(1.部分有序 2.小数组)建议使用insert sort  
note2:有稳定性  
res: time(insert) < time(select)  
  
>Shell sort P162  
key:数组中间隔h步长的元素是有序的, h从N/3递减为1  
key2:基于插入排序((只会交换相邻元素),shell sort是交换h步长的元素  
note:避免插入排序的极端情况--最后一位是最小元素--插入排序需要逐步移动到起始位置  
  
# 2.Merge Sort  
key:归并两个有序的数组;     
key2:递归到小数组;在进行归并(辅助数组N)    
note:有稳定性    
improvement:1.加快小数组排序(n < 8,则使用插入排序) 2.递归中交换参数避免重复辅助数组的赋值(MergeX file)      

# 3.Quick Sort  
key: partition切分   
improvement:1.n < 8,则使用插入排序 2.中位数作为a[lo] 3.random shuffle   
4.三向快排   
```java
// quicksort the subarray a[lo .. hi] using 3-way partitioning
void sort(Comparable[] a, int lo, int hi) {
    if (hi <= lo) return;
    int lt = lo, gt = hi;
    Comparable v = a[lo];
    int i = lo + 1;
    //TODO  小于v的值放在lt左侧 大于v的值放在gt右侧
    //TODO 等于v的值在 (lt,i)之间
    while (i <= gt) {
        int cmp = a[i].compareTo(v);
        if      (cmp < 0) exch(a, lt++, i++);       //a[i] < v  交换a[i]和a[lt]
        else if (cmp > 0) exch(a, i, gt--);         //a[i] > v  交换a[i]和a[gt]
        else              i++;
    }

    // a[lo..lt-1] < v = a[lt..gt] < a[gt+1..hi].
    sort(a, lo, lt-1);
    sort(a, gt+1, hi);
    assert isSorted(a, lo, hi);
}  
```

# 4.Priority Queue   
key: ordered array实现 或者 unordered array实现 或者 二叉树实现   
key2: 二叉树findMax+insert 都是是O(logN)  
note: 无法利用缓存 因为数组元素很少直接和相邻元素比较  
> heap   
key: 父节点序号k,则子节点为2k,2k+.  子节点为k,父节点为k/2   
key:sink swim要掌握   
```java
void sort(Comparable[] pq) {
    int n = pq.length;
    //TODO 构建有序堆
    //TODO 相当于从倒数第二层开始遍历到root  sink下沉构建
    for (int k = n/2; k >= 1; k--)
        sink(pq, k, n);
    //TODO 当前最大值pq[1]和最后一位交换 + 重新sink剩余(n-1)个元素
    while (n > 1) {
        exch(pq, 1, n--);
        sink(pq, 1, n);
    }
}

void sink(Comparable[] pq, int k, int n) {
    while (2*k <= n) {
        //TODO k的子节点2k, 2k+1 中val较大的值 == j
        int j = 2*k;
        if (j < n && less(pq, j, j+1)) j++;
        //TODO  不需要交换 则break
        if (!less(pq, k, j)) break;
        exch(pq, k, j);
        k = j;
    }
}
```


================================================
FILE: 3_Searching/BinarySearchTree.h
================================================
#ifndef BINARYSEARCHTREE_H_INCLUDED
#define BINARYSEARCHTREE_H_INCLUDED
#include"func.h"
/*
key: Int
val: string
*/

class BST{
private:
    class Node{
    public:
        int key;
        string val;
        int Size;
        Node* left;
        Node* right;
        Node(int k,string v,int s)
        :key(k),val(v),Size(s){
            left=NULL;
            right=NULL;
        }
    };
    Node* root;
public:
    BST(){root=NULL;}
    int sizeTree(Node* root){if(root==NULL) return 0;else return root->Size;}
    int sizeTree(){return sizeTree(root);}
    bool isEmpty(){return sizeTree()==0;}
    bool contains(int key){ return get(key)!="";}
    string get(int key){return get(root,key);}
    string get(Node* root,int key){
        if(root->key==key) return root->val;
        else if(root->key > key)
            return get(root->left,key);
        else
            return get(root->right,key);
    }
    //插入新元素 或者 更新val
    void put(int key,string val){
//        cout<<key<<" "<<val<<endl;
        root = put(root,key,val);
    }
    Node* put(Node* root,int key,string val){
        if(root==NULL)
            return new Node(key,val,1);
        if(root->key == key)
            root->val = val;
        else if(root->key > key)
            root->left = put(root->left,key,val);
        else
            root->right = put(root->right,key,val);

        root->Size = 1+sizeTree(root->left)+sizeTree(root->right);
        return root;
    }
    //删除极小值
    void deleteMin(){root=deleteMin(root);}
    Node* deleteMin(Node* root){
        if(root->left==NULL) return root->right;    //删除根节点
        root->left = deleteMin(root->left);
        root->Size = sizeTree(root->left) + sizeTree(root->right);
        return root;
    }
    //删除
    void deleteKey(int key){root = deleteKey(root,key);}
    Node* deleteKey(Node* root, int key){
        if(root->key > key)
            root->left = deleteKey(root->left,key);
        else if(root->key < key)
            root->right = deleteKey(root->right,key);
        else{
            if(root->right==NULL) return root->left;
            if(root->left==NULL) return root->right;
            //待删除节点 左右子树均不为空
            //右子树最小节点替换待删除节点
            Node* tmp = root;
            root = minLeaf(root->right);    //右子树最小节点
            root->right = deleteMin(tmp->right);
            root->left = tmp->left;
        }
    }
    //寻找最小leaf
    Node* minLeaf(Node* root){
        if(root->left==NULL) return root;
        else return minLeaf(root->left);
    }
    vector<int> print(){
        vector<int> BFS;
        queue<Node*> pq;
        pq.push(root);
        while(!pq.empty()){
            Node* tmp = pq.front();
            pq.pop();
            BFS.push_back(tmp->key);
            if(tmp->left!=NULL)
                pq.push(tmp->left);
            if(tmp->right!=NULL)
                pq.push(tmp->right);
        }
        return BFS;
    }

};


#endif // BINARYSEARCHTREE_H_INCLUDED


================================================
FILE: 3_Searching/BinarySearchTree_test.cpp
================================================
#include"BinarySearchTree.h"

int main(){
    BST* bst = new BST();
    std::ostringstream ss;
    for(int i=0;i<10;i++){
        ss << i;
        bst->put(i,ss.str());
    }

    bst->deleteKey(5);
    vector<int> BFS = bst->print();
    for(auto i:BFS) //按照层级输出
        cout<<i<<" ";
}


================================================
FILE: 3_Searching/README.md
================================================
代码链接:   
https://github.com/ISCASTEAM/Algorithm    

# Elementray Tables  
>无序链表   
key: 插入时间O(1)  查找时间O(N)  
note: 新元素直接插入链表头部  
>有序数组  
key:查找使用二分查找  
key: 插入时间O(N)  查找时间O(lgN)  
note: 插入元素  

# BinarySearchTree  
>1.基本实现  
get/put 时间复杂度O(1.39lgN)  
note: put操作 节点总是最后一层的leaf  
note: 随机的数据可能导致树的不平衡  复杂度为1.39lgN  

>2.有序性相关API  
flooring 向下取整    
向下取整:  tree中的节点 不大于给定查找值key  
ceiling 向上取整    
select rank  
max最后一层最右边的节点  min最后一层最左边的节点  
  
>3.删除delete  
删除的节点使用其右子树的最小值替换  
```java
private Node delete(Node x, Key key) {
    if (x == null) return null;

    int cmp = key.compareTo(x.key);
    if      (cmp < 0) x.left  = delete(x.left,  key);
    else if (cmp > 0) x.right = delete(x.right, key);
    else {
        if (x.right == null) return x.left;
        if (x.left  == null) return x.right;
        //TODO 待删除节点x 有左右子树
        //TODO min(x.right) x右子树最小节点替换待删除节点x
        Node t = x;
        x = min(t.right);   //min也是寻找最小节点的函数
        x.right = deleteMin(t.right);//删掉右子树最小值
        x.left = t.left;
    }
    x.size = size(x.left) + size(x.right) + 1;
    return x;
}
```
>4. 范围查找    
note: 中序遍历的二叉搜索树是有序的;  queue;    
note: 掌握inorder的递归代码格式  P268    
  
# BalancedSearchTree    
>1. 2-3树    
key数目是2, value数目是3(小于,中间,大于)    
note: 生长方式=自下而上    
理解 不同情况的下的插入变换方法    

>2. 红黑树    
note: 时间复杂度 1.00lgN  (对比二叉树),因为红黑树是平衡的    
note: 思考:新插入的节点都是红色的    

C++重构 lite版本的  代码链接:https://github.com/ISCASTEAM/Algorithm/tree/master/Tree
重点: 两种旋转 + 颜色转换 P280    

P275   
各种插入情况 汇总为三句话  
*c++插入实现*  
```cpp
RedBlackTree::Node* RedBlackTree::put(Node* h,int key,string val){
    if(h==NULL){
        _size ++;
        return new RedBlackTree::Node(key,val,_red);
    }
    if(h->_key == key) h->_val = val;
    else if(h->_key > key) h->left = put(h->left,key,val);
    else h->right = put(h->right,key,val);

    //TODO fix-up links
    if(isRed(h->right) && !isRed(h->left))  h = rotateLeft(h);
    if(isRed(h->left) && isRed(h->left->left))h = rotateRight(h);
    if(isRed(h->left) && isRed(h->right)) flipColors(h);

    return h;
}
```

*左右旋转 + 颜色转换*  
```cpp
Node* rotateRight(Node* h){
    Node* tmp = h->left;
    h->left = tmp->right;
    tmp->right = h;
    tmp->color = h->color;
    h->color = _red;
    return tmp;
}
Node* rotateLeft(Node* h){
    Node* tmp = h->right;
    h->right = tmp->left;
    tmp->left = h;
    tmp->color = h->color;
    h->color = _red;
    return tmp;
}
void flipColors(Node* h){
    h->color = _red;
    h->left->color = _black;
    h->right->color = _black;
}
```
*BST删除操作 P291*  


# HashTable  
*get put 都是常数时间*  
key:散列函数将key转化为数组索引; 处理碰撞冲突  
e.g java return (key.hashcode() & 0x7fffffff) % M  
note: 缺点 =》 有序性的API无法支持  
>1. 拉链法 P297  
相同key,链表串起来val   
  
>2. 线性探测法  
碰撞发生时,检测下一个位置是否为Null  
note: 删除操作,两个方法1.后面非空元素重新put一遍 2.置空NULL + 需要将后面元素前移一位    

  
# Application   
思考:  
稀疏矩阵 * vector如何在常数时间内完成  特别是当矩阵非常大时候  
P323  


================================================
FILE: 3_Searching/RedBlackTree.h
================================================
#include "func.h"

class RedBlackTree{
public:
    RedBlackTree():_root(NULL),_size(0){};
    string get(int key){ return get(_root,key);}
    void put(int key,string val){
        _root = put(_root,key,val);
        _root->color = _black;
    }

private:
    class Node{
    public:
        Node(int key,string val,bool color)
        :_key(key),_val(val),color(color){
            left = NULL;
            right = NULL;
        }
    //private:
        int _key;
        string _val;
        Node* left;
        Node* right;
        bool color;
    };
    Node* _root;
    int _size;

    string get(Node*,int);
    Node* put(Node*,int,string);

    Node* rotateRight(Node* h){
        Node* tmp = h->left;
        h->left = tmp->right;
        tmp->right = h;
        tmp->color = h->color;
        h->color = _red;
        return tmp;
    }
    Node* rotateLeft(Node* h){
        Node* tmp = h->right;
        h->right = tmp->left;
        tmp->left = h;
        tmp->color = h->color;
        h->color = _red;
        return tmp;
    }
    void flipColors(Node* h){
        h->color = _red;
        h->left->color = _black;
        h->right->color = _black;
    }
    bool isRed(Node* x){
        if(x == NULL) return false;
        return x->color == _red;
    }
    int getmin(Node* root){
        int key = -1;
        while(root!=NULL){
            key = root->_key;
            root =  root->left;
        }
        return key;
    }
    int getmax(Node* root){
        int key = -1;
        while(root!=NULL){
            key = root->_key;
            root = root->right;
        }
        return key;
    }
    void getKeys(Node* root,queue<int>& res){
        //inorder BFS
        if(root==NULL) return;
        getKeys(root->left,res);
        res.push(root->_key);
        getKeys(root->right,res);
    }
public:
    bool contains(int){ return _size;}
    int getsize(){return this->_size;}
    int getmin(){ return getmin(_root);}
    int getmax(){return getmax(_root);}
    void getKeys(queue<int>& res){ return getKeys(_root,res);}
    int getRoot(){return _root->_key;}
    //each path from root to leaf has the same black number
    bool isBalanced(){
        int black = 0;
        Node* root = _root;
        while(root!=NULL){
            if(!isRed(root)) black++;
            root = root->left;
        }
        return isBalanced(root,black);
    }
    bool isBalanced(Node* root, int numBlack){
        if(root==NULL) return numBlack==0;
        if(isRed(root)) numBlack--;
        return isBalanced(root->left,numBlack) &&isBalanced(root,numBlack);
    }
protected:
    const bool _red = true;
    const bool _black = false;

};

string RedBlackTree::get(Node* x, int key){
    while(x != NULL){
        if(x->_key == key) return x->_val;
        else if(x->_key > key) return get(x->left,key);
        else return get(x->right,key);
    }
    return NULL;
}

RedBlackTree::Node* RedBlackTree::put(Node* h,int key,string val){
    if(h==NULL){
        _size ++;
        return new RedBlackTree::Node(key,val,_red);
    }
    if(h->_key == key) h->_val = val;
    else if(h->_key > key) h->left = put(h->left,key,val);
    else h->right = put(h->right,key,val);

    //TODO fix-up links
    if(isRed(h->right) && !isRed(h->left))  h = rotateLeft(h);
    if(isRed(h->left) && isRed(h->left->left))h = rotateRight(h);
    if(isRed(h->left) && isRed(h->right)) flipColors(h);

    return h;
}




================================================
FILE: 3_Searching/RedBlackTree_test.cpp
================================================

#include "RedBlackTree.h"

int main(){
    string test = "ABCDEFG";
    RedBlackTree* rbt = new RedBlackTree();
    for(int i=0;i<7;i++){
//        cout<<string(1,test[i])<<endl;
        rbt->put(i,string(1,test[i]));
    }
    cout<<"root="<<rbt->getRoot()<<endl;
    cout<<"isBalanced="<<rbt->isBalanced()<<endl;
    cout<<"tree size="<<rbt->getsize()<<endl;
    cout<<"key min="<<rbt->getmin()<<endl;
    cout<<"key max="<<rbt->getmax()<<endl;

    cout<<endl;
    cout<<"Testing:"<<endl;
    //inorder to get key
    queue<int> res;
    rbt->getKeys(res);
    while(!res.empty()) {cout<<res.front()<<" "; res.pop();}
    cout<<endl;
    cout<<"get key==3, val="<<rbt->get(3)<<endl;
    return 0;
}


================================================
FILE: 4_Graphs/BFSPath.h
================================================
#ifndef BFSPATH_H_INCLUDED
#define BFSPATH_H_INCLUDED

#include"Graph.h"
class BFSPath{
private:
    vector<bool> marked;
    vector<int> edgeto;     //父节点
public:
    BFSPath(Graph* G){
        marked.resize(G->getV(),false);
        edgeto.reserve(G->getV());
    }

    void bfs(Graph* G, int s){
        /*
        input:  图结构Graph, 起始点S
        */
        queue<int> q;
        marked[s] = true;
        q.push(s);

        while(!q.empty()){
            int v = q.front();
            q.pop();
            for(int w:G->getadj(v)){
                if(!marked[w]){
                    edgeto[w] = v;          //区别于BFS代码
                    marked[w]=true;
                    q.push(w);
                }
            }
        }
    }
    //从起始点S到节点V的路径
    void pathTo(stack<int>& path,int s,int v){
        for(int i=v;i!=s;i=edgeto[i])
            path.push(i);
        path.push(s);
    }

};

#endif // BFSPATH_H_INCLUDED


================================================
FILE: 4_Graphs/BellmanFordSP.h
================================================
#ifndef BELLMANFORDSP_H_INCLUDED
#define BELLMANFORDSP_H_INCLUDED
#include"EdgeWeightedDigraph.h"
/*
定理:
1.distTo[S]=0,其他点无穷大。任意顺序relax所有边
2.1 重复V(顶点个数)轮  则停止
2.2 edgeTo[]存在负权重环  则停止

3.note:优化:
idea: 只有上一轮distTo[]发生变化的顶点指出的边才可能改变其他distTo[]的值,FIFO队列记录这样的顶点
==》 一轮代表执行一次relax(G,v)  ？？
queue1 保存即将被放松的顶点
bool[] 判断顶点是否已经存在于queue1
*/

class BellmanSP{
private:
    vector<double> distTo;
    vector<DiEdge> edgeTo;
    vector<bool> onQ;
    queue<int> fifo;        //待执行relax的顶点
    int relaxCalls;
    void relax(EdgeWeightedDigraph* G,int v){
        for(DiEdge e:G->getadj(v)){
            int w = e.to();
            if(distTo[w] > distTo[v]+e.getWeight()){            //注意符号方向
                distTo[w] = distTo[v]+e.getWeight();
                edgeTo[w]=e;
                //加入queue
                if(onQ[w]==false){
                    fifo.push(w);
                    onQ[w]=true;
                }
            }
            if(relaxCalls% G->getV()==0){
//                findNegativeCycle();  //这里我就不实现了
//                if(hasNCycle) return;
            }
        }
    }

public:
    BellmanSP(EdgeWeightedDigraph* G){
        edgeTo.resize(G->getV());
        distTo.resize(G->getV(),std::numeric_limits<double>::max());
        onQ.resize(G->getV(),false);
        relaxCalls=0;
    }

    void getBellmanSP(EdgeWeightedDigraph* G,int s){
        distTo[s]=0.0;
        onQ[s]=true;
        fifo.push(s);
//        while(!fifo.empty() && !hasNegativeCycle())
        while(!fifo.empty()){
            int v=fifo.front();
            fifo.pop();
            onQ[v]=false;
            relax(G,v);
        }
    }

    //其他API
    double getdistTo(int v){return distTo[v];}
    bool hasPathTo(int v){return distTo[v]<std::numeric_limits<double>::max();}
    vector<DiEdge> pathTo(int v){
        vector<DiEdge> pathRes;
        stack<DiEdge> path;
        if(!hasPathTo(v)) return vector<DiEdge>();
        for(DiEdge e=edgeTo[v]; e!=DiEdge();e=edgeTo[e.from()])
            path.push(e);
        while(!path.empty()){
            DiEdge e = path.top();
            path.pop();
            pathRes.push_back(e);
        }
        return pathRes;  //未包含起点
    }
};


#endif // BELLMANFORDSP_H_INCLUDED


================================================
FILE: 4_Graphs/DFSCC.h
================================================
#ifndef DFSCC_H_INCLUDED
#define DFSCC_H_INCLUDED

/*TODO   判断图存在多少个连通分量
思路:
所有未标记的节点 执行一遍完整DFS遍历
DFS代表从某一个节点出发 能到达的所有节点都会被标记
*/
#include"Graph.h"

class DFSCC{
private:
    vector<bool> marked;
    vector<int> id;     //id[v]表示所在连通集的编号
public:
    int setCount = 0;
    DFSCC(Graph* G){
        marked.reserve(G->getV());
        id.reserve(G->getV());
    }

    void dfs(Graph* G, int v){
        marked[v] = true;
        id[v]=setCount;             //在DFS代码上添加
        for(int w : G->getadj(v)){
            if(!marked[w])
                dfs(G,w);
        }

    }
    int getSetNum(Graph* G){
        for(int v=0;v<G->getV();v++){
            if(!marked[v]){
                dfs(G,v);
                setCount++;
            }
        }
        return setCount;
    }
};

#endif // DFSCC_H_INCLUDED


================================================
FILE: 4_Graphs/DFSDirectedCycle.h
================================================
#ifndef DFSDIRECTEDCYCLE_H_INCLUDED
#define DFSDIRECTEDCYCLE_H_INCLUDED
#include"Digraph.h"
/*
有向图 判断是否存在有向环

不存在环路 topological order算法的前提
*/

class DFSDirectedCycle{
private:
    vector<bool> marked;
    vector<int> edgeTo;
    vector<bool> onstack;
    stack<int> cycle;

public:
    DFSDirectedCycle(Digraph* G){
        marked.resize(G->getV(),false);
        edgeTo.reserve(G->getV());
        onstack.resize(G->getV(),false);
    }
    bool hasCycle(Digraph* G){
        for(int v=0;v<G->getV();v++){
           if(!marked[v] && cycle.empty())
                dfs(G,v);
        }
        if(cycle.empty()) return false;
        else return true;
    }
    void dfs(Digraph* G,int v){
        marked[v]=true;
        onstack[v]=true;

        //正常的dfs流程
        for(int w:G->getadj(v)){
            if(!cycle.empty()) return;
            else if(!marked[w]){
                edgeTo[w]=v;
                dfs(G,w);
            }
            //判断是否构成环路
            else if(onstack[w]){
                for(int tmp=v;tmp!=w;tmp=edgeTo[tmp])
                    cycle.push(tmp);
                cycle.push(w); //子节点w是环的终点
            }
        }

        onstack[v]=false;
    }
};


#endif // DFSDIRECTEDCYCLE_H_INCLUDED


================================================
FILE: 4_Graphs/DFSTopo.h
================================================
#ifndef DFSTOPO_H_INCLUDED
#define DFSTOPO_H_INCLUDED
#include"Digraph.h"
#include"EdgeWeightedDigraph.h"
/*
拓扑排序  DFS+一行代码

BFS是将入度为零的先加入queue
*/

class DFSTopo{
private:
    vector<bool> marked;
    stack<int> reversePost;

public:
    DFSTopo(Digraph* G){
        marked.resize(G->getV(),false);
    }

    vector<int> getTopo(Digraph* G){
        for(int v=0;v<G->getV();v++){     //可能是多连通分量图
            if(!marked[v])
                dfs(G,v);
        }

        vector<int> res;
        while(!reversePost.empty()){
            res.push_back(reversePost.top());
            reversePost.pop();
        }
        return res;
    }

    void dfs(Digraph* G,int v){
        marked[v] = true;
        for(int w:G->getadj(v)){
            if(!marked[w])
                dfs(G,w);
        }
        reversePost.push(v);
    }

//****************************关于加权Weighted 有向图的重载
    DFSTopo(EdgeWeightedDigraph* G){
        marked.resize(G->getV(),false);
    }

    vector<int> getTopo(EdgeWeightedDigraph* G){
        for(int v=0;v<G->getV();v++){     //可能是多连通分量图
            if(!marked[v])
                dfs(G,v);
        }

        vector<int> res;
        while(!reversePost.empty()){
            res.push_back(reversePost.top());
            reversePost.pop();
        }
        return res;
    }

    void dfs(EdgeWeightedDigraph* G,int v){
        marked[v] = true;
        for(DiEdge e:G->getadj(v)){
            if(!marked[e.to()])
                dfs(G,e.to());
        }
        reversePost.push(v);
    }
};
#endif // DFSTOPO_H_INCLUDED


================================================
FILE: 4_Graphs/DiEdge.h
================================================
#ifndef DIEDGE_H_INCLUDED
#define DIEDGE_H_INCLUDED
#include "func.h"
/*
区别于无向边,v->w == v,w具有固定的含义
API from v to w
*/
class DiEdge{
private:
    int v;
    int w;
    double weight;

public:
    DiEdge()
    :v(0),w(0),weight(0.0){}
    DiEdge(int v,int w,double weight)
    :v(v),w(w),weight(weight){}
    int from()const { return v;}
    int to()const {return w;}
    double getWeight()const {return weight;}        //const成员函数 不改变类对象的内部数据

    friend bool operator<(const DiEdge& a,const DiEdge& b);
    friend bool operator>(const DiEdge& a,const DiEdge& b);
    friend bool operator==(const DiEdge& a,const DiEdge& b);
    friend bool operator!=(const DiEdge& a,const DiEdge& b);

};

bool operator<(const DiEdge& a,const DiEdge& b){
    return a.getWeight() < b.getWeight();
}
bool operator>(const DiEdge& a,const DiEdge& b){
    return a.getWeight() > b.getWeight();
}
bool operator==(const DiEdge& a,const DiEdge& b){
    return a.getWeight()==b.getWeight() && a.from()==b.from() && a.to()==b.to();
}

bool operator!=(const DiEdge& a,const DiEdge& b){
    return a.getWeight()!=b.getWeight() || a.from()!=b.from() || a.to()!=b.to();
}

#endif // DIEDGE_H_INCLUDED


================================================
FILE: 4_Graphs/Digraph.h
================================================
#ifndef DIGRAPH_H_INCLUDED
#define DIGRAPH_H_INCLUDED
#include "func.h"

class Digraph{
private:
    int V;
    int E;
    vector<vector<int>> adj;            //邻接链表
    void addEdge(int v,int w){
        adj[v].push_back(w);            //区别于无向图
    }
public:
    Digraph(int v):V(v),E(0){adj.resize(v,vector<int>());};
    Digraph(string file){
        std::ifstream infile(file);
        string tmp;
        int lineNum = 0;
        while(std::getline(infile,tmp)){
            std::istringstream iss(tmp);
            int v1,v2;
            if(lineNum==0) {iss>>V; adj.resize(V,vector<int>());}
            else if(lineNum==1) iss>>E;
            else {
                iss>>v1>>v2;
                addEdge(v1,v2);
            }
            lineNum++;
        }
    };
    int getV(){return V;}
    int getE(){return E;}
    int degree(int v){return adj[v].size();}
    vector<int> getadj(int v){return adj[v];}

    //反转图
    Digraph* reverseG(){
        Digraph* revG = new Digraph(V);
        for(int v=0;v<V;v++){
            for(int w : getadj(v))
                revG->addEdge(w,v);
        }
        return revG;
    }

};

#endif // DIGRAPH_H_INCLUDED


================================================
FILE: 4_Graphs/DijkstraSP.h
================================================
#ifndef DIJKSTRASP_H_INCLUDED
#define DIJKSTRASP_H_INCLUDED
#include"DiEdge.h"
#include"EdgeWeightedDigraph.h"
/*
非负权重 有向图
类似于即时的prim算法
1.将dist[Start]=0,其他distTo[]初始化为无穷大
2.重复将distTo[]中最小非树节点V =>relax(G,V)
3.直到所有顶点都在树或所有非树顶点distTo无限大
*/

class DijkstraSP{
private:
    vector<DiEdge> edgeTo;
    vector<double> distTo;
    map<int,double> minPQ;      //非树节点vertex和distTo
    int getPQmin(){
        double minval = std::numeric_limits<double>::max();
        int key = 0;
        for(map<int,double>::iterator iter=minPQ.begin();iter!=minPQ.end();iter++){
            if(iter->second < minval){
                key = iter->first;
                minval = iter->second;
            }
        }
        return key;
    }
    void erasePQ(int v){
        map<int,double>::iterator it = minPQ.find(v);
        minPQ.erase(it);
    }

    //relax 松弛API
    void relax(EdgeWeightedDigraph* G,int v){
        for(DiEdge e:G->getadj(v)){
            int v=e.from();
            int w=e.to();
            //w到s的距离更新
            if(distTo[v]+e.getWeight() < distTo[w]){
                distTo[w]= distTo[v]+e.getWeight();
                edgeTo[w]=e;
                minPQ[w]=distTo[w];     //update or insert
            }
        }
    }

public:
    DijkstraSP(EdgeWeightedDigraph* G,int s){
        edgeTo.resize(G->getV());
        distTo.resize(G->getV(),std::numeric_limits<double>::max());
    }
    void getSP(EdgeWeightedDigraph* G,int s){
        distTo[s]=0.0;
        minPQ[s]=distTo[s];
        while(!minPQ.empty()){
            int v = getPQmin();
            erasePQ(v);
            relax(G,v);
        }
    }

    //其他API
    double getdistTo(int v){return distTo[v];}
    bool hasPathTo(int v){return distTo[v]<std::numeric_limits<double>::max();}
    vector<DiEdge> pathTo(int v){
        vector<DiEdge> pathRes;
        stack<DiEdge> path;
        if(!hasPathTo(v)) return vector<DiEdge>();
        for(DiEdge e=edgeTo[v]; e!=DiEdge();e=edgeTo[e.from()])
            path.push(e);
        while(!path.empty()){
            DiEdge e = path.top();
            path.pop();
            pathRes.push_back(e);
        }
        return pathRes;  //未包含起点
    }
};
#endif // DIJKSTRASP_H_INCLUDED


================================================
FILE: 4_Graphs/DirectedGraph_test.cpp
================================================
#include"Digraph.h"
#include"DFSDirectedCycle.h"
#include"DFSTopo.h"

int main(){
    Digraph* G = new Digraph("./data/tinyDAG.txt");      //tinyDAG无环有向图

    //基础测试
    cout<<G->getE()<<endl;
    cout<<G->getV()<<endl;
    cout<<G->degree(0)<<endl;

    //单点路径问题(DFS判断存在性 BFS求最短)

    //有向图是否存在环？
    cout<<endl;
    DFSDirectedCycle* dfsDC = new DFSDirectedCycle(G);
    cout<<true<<endl;
    cout<<dfsDC->hasCycle(G)<<endl;

    //顶点的三种遍历顺序
    //topological拓扑排序 解决优先级问题
    //思路:  DFS+ revesePost顺序 证明P376  + P388 BFS
    cout<<endl;
    DFSTopo* dfsTopo = new DFSTopo(G);
    for(auto i:dfsTopo->getTopo(G))
        cout<<i<<" ";


    //思考题:
    //P380 强连通分量 Kosaraju算法
    //总结P385
    return 0;
}


================================================
FILE: 4_Graphs/Edge.h
================================================
#ifndef EDGE_H_INCLUDED
#define EDGE_H_INCLUDED

#include"func.h"
/*
有权重的无向图
边
*/

class Edge{
private:
    int v;
    int w;
    double weight;

public:
    Edge()
    :v(0),w(0),weight(0.0){}
    Edge(int v,int w,double weight)
    :v(v),w(w),weight(weight){}
    double getWeight()const {return weight;}

    //either other获取边的两个顶点
    int other(int vTmp){
        if(vTmp==v) return w;
        else return v;
    }
    int either(){return v;}

    //compare重载
    //const成员函数不允许修改类数据 + const对象只能使用const函数
    friend bool operator<(const Edge& a,const Edge& b);
    friend bool operator>(const Edge& a,const Edge& b);
    friend bool operator==(const Edge& a,const Edge& b);

};

bool operator<(const Edge& a,const Edge& b){
    return a.getWeight() < b.getWeight();
}
bool operator>(const Edge& a,const Edge& b){
    return a.getWeight() > b.getWeight();
}
bool operator==(const Edge& a,const Edge& b){
    return a.getWeight() == b.getWeight();
}

#endif // EDGE_H_INCLUDED


================================================
FILE: 4_Graphs/EdgeWeightedDigraph.h
================================================
#ifndef EDGEWEIGHTEDDIGRAPH_H_INCLUDED
#define EDGEWEIGHTEDDIGRAPH_H_INCLUDED
#include"DiEdge.h"
/*
加权 有向图的定义
*/
class EdgeWeightedDigraph{
private:
    int V;
    int E;
    vector<vector<DiEdge>> adj;
    void addEdge(int v,int w,double weight){
        DiEdge tmp(v,w,weight);
        adj[v].push_back(tmp);
    }
public:
    EdgeWeightedDigraph(string file){
        std::ifstream infile(file);
        string tmp;
        int lineNum = 0;
        while(std::getline(infile,tmp)){
            std::istringstream iss(tmp);
            int v1,v2;
            double weight;
            if(lineNum==0) {iss>>V; adj.resize(V,vector<DiEdge>());}
            else if(lineNum==1) iss>>E;
            else {
                iss>>v1>>v2>>weight;
                addEdge(v1,v2,weight);
            }
            lineNum++;
        }
    }
    int getV(){return V;}
    int getE(){return E;}
    int degree(int v){return adj[v].size();}
    vector<DiEdge> getadj(int v){ return adj[v];}
    set<DiEdge> getAllEdges(){
        set<DiEdge> allEdges;
        for(vector<DiEdge> tmp:adj){
            for(DiEdge e:tmp){
                allEdges.insert(e);
            }
        }
        return allEdges;
    }
};


#endif // EDGEWEIGHTEDDIGRAPH_H_INCLUDED


================================================
FILE: 4_Graphs/EdgeWeightedGraph.h
================================================
#ifndef EDGEWEIGHTEDGRAPH_H_INCLUDED
#define EDGEWEIGHTEDGRAPH_H_INCLUDED
#include"func.h"
#include"Edge.h"
/*
实现带带权重的无向图
*/
class EdgeWeightedGraph{
private:
    int V;
    int E;
    vector<vector<Edge>> adj;
    void addEdge(int v,int w,double weight){
        Edge tmp(v,w,weight);
        adj[v].push_back(tmp);
        adj[w].push_back(tmp);
    }
public:
    EdgeWeightedGraph(string file){
        std::ifstream infile(file);
        string tmp;
        int lineNum = 0;
        while(std::getline(infile,tmp)){
            std::istringstream iss(tmp);
            int v1,v2;
            double weight;
            if(lineNum==0) {iss>>V; adj.resize(V,vector<Edge>());}
            else if(lineNum==1) iss>>E;
            else {
                iss>>v1>>v2>>weight;
                addEdge(v1,v2,weight);
            }
            lineNum++;
        }
    }
    int getV(){return V;}
    int getE(){return E;}
    int degree(int v){return adj[v].size();}
    vector<Edge> getadj(int v){ return adj[v];}
    set<Edge> getAllEdges(){
        set<Edge> allEdges;
        for(vector<Edge> tmp:adj){
            for(Edge e:tmp){
                allEdges.insert(e);
            }
        }
        return allEdges;
    }
};


#endif // EDGEWEIGHTEDGRAPH_H_INCLUDED


================================================
FILE: 4_Graphs/Graph.h
================================================
#ifndef GRAPH_H_INCLUDED
#define GRAPH_H_INCLUDED

#include "func.h"
class Graph{
private:
    int V;
    int E;
    vector<vector<int>> adj;            //邻接链表
    void addEdge(int v,int w){
        adj[v].push_back(w);
        adj[w].push_back(v);
    }
public:
    Graph(int v):V(v),E(0){adj.resize(v,vector<int>());};
    Graph(string file){
        std::ifstream infile(file);
        string tmp;
        int lineNum = 0;
        while(std::getline(infile,tmp)){
            std::istringstream iss(tmp);
            int v1,v2;
            if(lineNum==0) {iss>>V; adj.resize(V,vector<int>());}
            else if(lineNum==1) iss>>E;
            else {
                iss>>v1>>v2;
                addEdge(v1,v2);
            }
            lineNum++;
        }
    };
    int getV(){return V;}
    int getE(){return E;}
    int degree(int v){return adj[v].size();}
    vector<int> getadj(int v){return adj[v];}

};


#endif // GRAPH_H_INCLUDED


================================================
FILE: 4_Graphs/KruskalMST.h
================================================
#ifndef KRUSKALMST_H_INCLUDED
#define KRUSKALMST_H_INCLUDED
#include"EdgeWeightedGraph.h"
#include"UnionFind.h"
/*
克鲁斯卡尔
idea: 不断从所有边中寻找最小值,要求不能构成环路(不在同一个连通集)
note: 相同于不断合并不同的连通分量
note: unionFind数据结构
*/

class KruskalMST{
private:
    queue<Edge> result;
    double totalWeight;
    priority_queue<Edge,vector<Edge>,std::greater<Edge>> minpq;     //初始加入所有边

public:
    KruskalMST(EdgeWeightedGraph* G)
    :totalWeight(0.0){
        UnionFind* uf = new UnionFind(G->getV());
        for(Edge e:G->getAllEdges())
            minpq.push(e);

        //生成MST
        while(!minpq.empty() && result.size()<G->getV()-1){
            Edge e = minpq.top();
            minpq.pop();
            int v=e.either(); int w=e.other(v);

            //已经在同一个连通集合
            if(uf->connected(v,w)) continue;
            else{
                uf->unionV(v,w);
                result.push(e);
                totalWeight += e.getWeight();
            }
        }
    }
    queue<Edge> getRes(){ return result;}
    double getWeight(){return totalWeight;}

};

#endif // KRUSKALMST_H_INCLUDED


================================================
FILE: 4_Graphs/LazyPrimMST.h
================================================
#ifndef LAZYPRIMMST_H_INCLUDED
#define LAZYPRIMMST_H_INCLUDED

#include "EdgeWeightedGraph.h"

/*
延时删除的prim最小生成树
pre: 图是连通
idea: 随机起点 + 可到达边的最小值加入tree
note: 删除无效边(可达边的两个节点都已经标记)
*/

class LazyPrimMST{
private:
    queue<Edge> mst;
    double totalWeight;
    vector<bool> marked;
    priority_queue<Edge,vector<Edge>,std::greater<Edge>> minpq;

public:
    LazyPrimMST(EdgeWeightedGraph* G):totalWeight(0.0){
        marked.resize(G->getV(),false);
    }

    queue<Edge> getMST(EdgeWeightedGraph* G){
        visit(G,0);
        while(!minpq.empty()){
            Edge e = minpq.top();
            minpq.pop();
            int v = e.either();
            int w = e.other(v);
            if(marked[v] && marked[w]) continue;
            //加入最小生成树
            mst.push(e);
            totalWeight += e.getWeight();
            //visit新顶点
            if(!marked[v]) visit(G,v);
            else visit(G,w);
        }
        return mst;
    }

    //节点v所有可达边
    void visit(EdgeWeightedGraph* G,int v){
        marked[v]=true;
        for(Edge e : G->getadj(v)){
            int w = e.other(v);
            if(!marked[w])
                minpq.push(e);
        }
    }

    double getWeight(){ return totalWeight;}

};

#endif // LAZYPRIMMST_H_INCLUDED


================================================
FILE: 4_Graphs/MinTree_test.cpp
================================================
#include"EdgeWeightedGraph.h"
#include"LazyPrimMST.h"
#include"PrimMST.h"
#include"KruskalMST.h"

int main(){
    EdgeWeightedGraph* G = new EdgeWeightedGraph("./data/tinyEWG.txt");      //tinyDAG无环有向图

    //基础测试
    cout<<G->getE()<<endl;
    cout<<G->getV()<<endl;
    cout<<G->degree(0)<<endl;

    //最小生成树测试
    //1.延时删除Prim算法
    cout<<endl;
    LazyPrimMST* mst = new LazyPrimMST(G);
    queue<Edge> res = mst->getMST(G);
    while(!res.empty()){
        Edge e = res.front();
        res.pop();
        cout<<e.either()<<"-"<<e.other(e.either())<<" "<<e.getWeight()<<endl;
    }
    cout<<"min total_weight = "<<mst->getWeight()<<endl;
    cout<<endl;


    //2.即时删除Prim算法
    PrimMST* pmst = new PrimMST(G);
    vector<Edge> res2 = pmst->getMST(G);
    for(Edge e:res2){
        cout<<e.either()<<"-"<<e.other(e.either())<<" "<<e.getWeight()<<endl;
    }
    cout<<"min total_weight = "<<pmst->getWeight()<<endl;
    cout<<endl;


    //3.克鲁斯卡尔算法
    KruskalMST* kmst = new KruskalMST(G);
    queue<Edge> res3 = kmst->getRes();
    while(!res3.empty()){
        Edge e = res3.front();
        res3.pop();
        cout<<e.either()<<"-"<<e.other(e.either())<<" "<<e.getWeight()<<endl;
    }
    cout<<"min total_weight = "<<kmst->getWeight()<<endl;



    return 0;
}


================================================
FILE: 4_Graphs/PrimMST.h
================================================
#ifndef PRIMMST_H_INCLUDED
#define PRIMMST_H_INCLUDED

#include "EdgeWeightedGraph.h"

/*
即时删除的prim最小生成树
idea: 随机起点 + 可到达边的最小值加入tree
note:
1.lazy模式 会将Edge都加入queue ==》 priority queue
2.即时 在加入queue进行判断: 无效边+非最小边 被拒绝
3.数据结构:
edgeTo[w] w距离tree最近的edge 或者NULL
dist[w]=edgeTo[w].weight
indexQueue 用map<w,weight>实现,保存待遍历的横切边

相比较于Lazy模式  indexPQ中的可达边数量是常数级别
*/

class PrimMST{
private:
    vector<Edge> edgeTo;
    vector<double> distTo;
    vector<bool> marked;
    map<int,double> indexPQ;
    double totalWeight;

    //indexPQ min_val对应的顶点
    int getPQmin(){
        double minval = std::numeric_limits<double>::max();
        int key = 0;
        for(map<int,double>::iterator iter=indexPQ.begin();iter!=indexPQ.end();iter++){
            if(iter->second < minval){
                key = iter->first;
                minval = iter->second;
            }
        }
        return key;
    }
    void erasePQ(int v){
        map<int,double>::iterator it = indexPQ.find(v);
        indexPQ.erase(it);
    }

public:
    PrimMST(EdgeWeightedGraph* G):totalWeight(0.0){
        edgeTo.resize(G->getV());           //reserve并不会真实开辟空间
        distTo.resize(G->getV(),std::numeric_limits<double>::max());
        marked.resize(G->getV(),false);
    }

    vector<Edge> getMST(EdgeWeightedGraph* G){
        distTo[0]=0.0;
        indexPQ[0]=0.0;
        while(!indexPQ.empty()){
            int v = getPQmin();     //相比较于Lazy模式  indexPQ中的可达边数量是常数级别
            totalWeight += indexPQ[v];
            erasePQ(v);
            visit(G,v);     //最近节点加入树中
        }
        return edgeTo;
    }

    //节点v所有可达边
    void visit(EdgeWeightedGraph* G,int v){
        marked[v]=true;
        for(Edge e: G->getadj(v)){
            int w = e.other(v);
            if(marked[w]) continue;
            else if(e.getWeight() >= distTo[w]) continue;
            else{
                edgeTo[w] = e;
//                cout<<e.either()<<"-"<<e.other(e.either())<<" "<<e.getWeight()<<endl;
                distTo[w] = e.getWeight();
                indexPQ[w]=distTo[w];           //map中不存在w 则会添加
            }
        }
    }

    double getWeight(){ return totalWeight;}
    vector<Edge> getEdgeTo(){ return edgeTo;}

};

#endif // PRIMMST_H_INCLUDED


================================================
FILE: 4_Graphs/README.md
================================================
代码链接:
xxxxxxxxxxxx
  
# 无向图  
Graph.h 实现图的API 邻接链表保存边  
DFS BFS的核心代码  
>应用  
连通性||单点路径 DFS or BFS  
单点最短路径  BFS  
其它:  
1.连通分量个数  DFS         
2.检测环 DFS  
3.双色问题 DFS  
   
# 有向图  
Digraph.h 实现图的API 邻接链表保存边  
>应用  
单点可达性||单点有向路径 DFS orBFS  
单点最短路径 BFS  
其它:  
1.有向环检测  DFS  
2.拓扑排序 DFS+stack  
  
# 最小生成树  
Edge.h 实现有权重边的API  
EdgeWeightedGraph.h 实现图的API  
>prim 普里姆算法  
所有可达边中选择最小边加入Tree(注意跳过失效边)  
1.延时更新   
marked[] 记录顶点已在最小树上  
priority_queue记录有效的可达边  
lazyPrimMST.h  
2.即时更新  
distTo[w]记录w到最小树的距离,跳过Edge.Weight > distTo[w]的顶点  
map_indexMin_queue 记录有效横切边 (常数空间大小)  
  
>kruskal 克鲁斯卡尔算法  
所有边的最小值加入Tree(跳过v,w在同一个连通集的边,即新加入的边不构成环路)  
终止条件:  
所有边都遍历完 或者 MST的边数==G的顶点数目-1  
UnionFind数据结构  
UF判断Edge 的v,w顶点,从而跳过或者union(v,w)  
  
# 最短路径  
加权 有向图  
DiEdge.h 实现有权重,有方向边的API  
EdgeWeightedDigraph.h 实现图的API  
>Dijkstra 算法  
前提:  边的权重必须为正  
由起点开始,按照最小distTo[]顺序,relax松弛所有顶点  
终止条件: map map_indexMin_queue为空  
  
> 拓扑排序  
前提: 无环图  
线性时间解决问题=> 按照topo顺序relax顶点  
拓展: 如何计算最长路径？变换符号 或者取权重相反数  
关键路径定义:  限制优先级问题得到有向图,计算最长路径  
  
> Bellman-Ford 算法  
>基于队列  
前提: 不存在负权重的环  
任意顺序relax顶点,重复V轮  
优化: 一轮意味着执行一次relax？ 只有relax才可能导致distTo的变化  
queue fifo保存即将被放松的顶点  
bool[] 判断顶点是否已经存在于queue  
  
应用: 金融套汇问题  =》 换汇的乘积转换为ln求和 =》寻找负权重的环  ==》获利  


================================================
FILE: 4_Graphs/ShortestPath_test.cpp
================================================
#include"DijkstraSP.h"
#include"TopoLongestPath.h"
#include"BellmanFordSP.h"

int main(){
    EdgeWeightedDigraph* G = new EdgeWeightedDigraph("./data/tinyEWD.txt");      //tinyDAG无环有向图

    //基础测试
    cout<<G->getE()<<endl;
    cout<<G->getV()<<endl;
    cout<<G->degree(0)<<endl;

    //Dijkstra shortest path测试
    cout<<endl;
    int startV=0;
    int endV = 6;
    DijkstraSP* dSP = new DijkstraSP(G,startV);
    dSP->getSP(G,startV);
    cout<<"hasPathTo endVertex="<<endV<<" is "<<(bool)dSP->hasPathTo(endV)<<endl;
    double totalW=0.0;
    for(DiEdge e:dSP->pathTo(endV)){
        cout<<e.from()<<"-"<<e.to()<<" "<<e.getWeight()<<endl;
        totalW += e.getWeight();
    }
    cout<<"from 0 to 6, shortestpath="<<totalW<<endl;
    cout<<endl;


    //无环图 LongestPath测试
    startV=5;
    endV = 2;
    G = new EdgeWeightedDigraph("./data/tinyEWDAG.txt");
    TopoLP* topoLP = new TopoLP(G);
    topoLP->getTopoLP(G,startV);
    totalW=0.0;
    for(DiEdge e:topoLP->pathTo(endV)){
        cout<<e.from()<<"-"<<e.to()<<" "<<e.getWeight()<<endl;
        totalW += e.getWeight();
    }
    cout<<"from 5 to 2, longestpath="<<totalW<<endl;
    //思考:
    //应用: 限制优先级问题
    //idea: 将限制条件转化为有向图 P431  => 加权有向图最长路径


    //一般性问题  Bellman-Ford
    //不存在权重值之和为负的还 有向图
    cout<<endl;
    startV=0;
    endV = 3;
    G = new EdgeWeightedDigraph("./data/tinyEWDnc.txt");
    BellmanSP* bSP = new BellmanSP(G);
    bSP->getBellmanSP(G,startV);
    totalW=0.0;
    for(DiEdge e:bSP->pathTo(endV)){
        cout<<e.from()<<"-"<<e.to()<<" "<<e.getWeight()<<endl;
        totalW += e.getWeight();
    }
    cout<<"from 0 to 1, longestpath="<<totalW<<endl;

    //思考:
    //金融套汇问题  ==》 转化为寻找负权重之和的环  P444

}


================================================
FILE: 4_Graphs/TopoLongestPath.h
================================================
#ifndef TOPOSHORTESTPATH_H_INCLUDED
#define TOPOSHORTESTPATH_H_INCLUDED
#include"EdgeWeightedDigraph.h"
#include"DFSTopo.h"

/*
Dijkstra 非负权重的有向图单源最短路径

TopoSp 无环有向图
1.线性时间找最短路径 + Weight可以为负 + 变换权重正负号寻找最长路径
idea:
按照topological顺序relax所有顶点
证明 P426

note: 1.将weight全部取相反数  或者2.交换所有大小判断符号
*/

class TopoLP{
private:
    vector<double> distTo;
    vector<DiEdge> edgeTo;
    void relax(EdgeWeightedDigraph* G,int v){
        for(DiEdge e:G->getadj(v)){
            int w = e.to();
            if(distTo[w] < distTo[v]+e.getWeight()){            //注意符号方向
                distTo[w] = distTo[v]+e.getWeight();
                edgeTo[w]=e;
            }
        }
    }

public:
    TopoLP(EdgeWeightedDigraph* G){
        edgeTo.resize(G->getV());
        distTo.resize(G->getV(),std::numeric_limits<double>::min());        //double最小值
    }
    void getTopoLP(EdgeWeightedDigraph* G,int s){
        distTo[s]=0.0;
        DFSTopo* topo_order = new DFSTopo(G);
        for(int v:topo_order->getTopo(G))
            relax(G,v);
    }

    //其他API
    double getdistTo(int v){return distTo[v];}
    bool hasPathTo(int v){return distTo[v] > std::numeric_limits<double>::min();}
    vector<DiEdge> pathTo(int v){
        vector<DiEdge> pathRes;
        stack<DiEdge> path;
        if(!hasPathTo(v)) return vector<DiEdge>();
        for(DiEdge e=edgeTo[v]; e!=DiEdge();e=edgeTo[e.from()])
            path.push(e);
        while(!path.empty()){
            DiEdge e = path.top();
            path.pop();
            pathRes.push_back(e);
        }
        return pathRes;  //未包含起点
    }
};

#endif // TOPOSHORTESTPATH_H_INCLUDED


================================================
FILE: 4_Graphs/UndirectedGraph_test.cpp
================================================
#include"Graph.h"
#include"DFSCC.h"
#include"BFSPath.h"

int initG(){
    std::ifstream infile("./data/tinyG.txt");
    string tmp;
    int E,V;
    int lineNum = 0;
    while(std::getline(infile,tmp)){
        std::istringstream iss(tmp);
        int v1,v2;
        if(lineNum==0) iss>>E;
        else if(lineNum==1) iss>>V;
        else iss>>v1>>v2;
        lineNum++;
    }
}
int main(){
    Graph* G = new Graph("./data/tinyG.txt");

    //基础测试
    cout<<G->getE()<<endl;
    cout<<G->getV()<<endl;
    cout<<G->degree(0)<<endl;

    //DFS得到图中连通集的数量
    cout<<endl;
    DFSCC* cc = new DFSCC(G);
    cout<<cc->getSetNum(G)<<endl;   //3个连通分量
    //DFS思考:
    //判断是否存在从节点V到节点W的路径？
    //判断图是否存在环？
    //判断图是否可以只用两种颜色标记？
    //P599 两点之间最长路径 DFS变型



    //BFS得到最短单点路径问题
    cout<<endl;
    BFSPath* bfs = new BFSPath(G);
    stack<int> path;
    bfs->bfs(G,0);
    bfs->pathTo(path,0,3);
    while(!path.empty()){
        cout<<path.top()<<" ";
        path.pop();
    }

    return 0;
}


================================================
FILE: 4_Graphs/UnionFind.h
================================================
#ifndef UNIONFIND_H_INCLUDED
#define UNIONFIND_H_INCLUDED
#include"func.h"
/*
实现weighted union find
小树加入大树 从而减少树的高度
*/

class UnionFind{
private:
    vector<int> parent;
    vector<int> sz;
    int unionCount;
public:
    UnionFind(int vertexNum)
    :unionCount(vertexNum){
        parent.resize(vertexNum);
        sz.resize(vertexNum,1);
        for(int i=0;i<vertexNum;i++)
            parent[i]=i;
    }
    int getUnionNum(){return unionCount;}

    //API= find,union,connected
    bool connected(int v,int w){
        return findRoot(v) == findRoot(w);
    }
    int findRoot(int p){
        while(p != parent[p])
            p=parent[p];
        return p;
    }
    void unionV(int v,int w){
        int i=findRoot(v);
        int j=findRoot(w);
        if(i==j) return;
        if(sz[i]<sz[j]){parent[i]=j; sz[j]+=sz[i];}
        else{parent[j]=i; sz[i]+=sz[j];}
        unionCount--;
    }
};

#endif // UNIONFIND_H_INCLUDED


================================================
FILE: 5_Strings/Huffman.h
================================================
#ifndef HUFFMAN_H_INCLUDED
#define HUFFMAN_H_INCLUDED
#include"func.h"
class Huffman{
private:
    const int R = 256;
    class Node{
//    private:
    public:
        char ch;        //非叶子节点是'\0'
        int freq;
        Node* left;
        Node* right;  //leaf.left and right is NULL

        Node(char c,int f,Node* l,Node*r)
        :ch(c),freq(f),left(l),right(r){}
        char getVal(){return ch;}
        bool isLeaf(){return left==NULL&&right==NULL;}
        bool operator<(const Node&that){return freq <that.freq;}
    };

    Node* buildTrie(const vector<int>& freq){
        priority_queue<Node*,vector<Node*>,std::greater<Node*>> minPQ;
        for(int i=0;i<R;i++)
            if(freq[i]>0)
                minPQ.push(new Node(i,freq[i],NULL,NULL));
        while(minPQ.size()>=2){
            Node* left = minPQ.top();
            minPQ.pop();
            Node* right = minPQ.top();
            minPQ.pop();
            Node* parent = new Node('\0',left->freq+right->freq,
                                    left,right);
            minPQ.push(parent);
        }
        Node* root = minPQ.top();
        minPQ.pop();
        return root;
    }
    void buildCode(vector<string>& st,Node* root,string s){
        if(!root->isLeaf()){
            buildCode(st,root->left,s+"0");
            buildCode(st,root->right,s+"1");
        }else{
            st[(int)root->getVal()]=s;
        }

    }

public:
    vector<string> st;
    Huffman(){st.resize(R,"");}
    int getR(){return R;}

    void compress(string s){
        //1.统计字符频率
        vector<int> freq(R,0);
        for(char c:s)
            freq[c]++;

        //2.构建huffman trie tree
        Node* root = buildTrie(freq);

        //3.构建编译表
        buildCode(st,root,"");
    }
    /*  encode compress
        前提:  已经得到Huffman编译表
        这里简单的将"|"作为分隔符
    */
    string encodeStr(string str){
        string ans="";
        for(char c:str)
            ans += st[c]+"|";
        return ans;
    }

};


#endif // HUFFMAN_H_INCLUDED


================================================
FILE: 5_Strings/Huffman_test.cpp
================================================
#include"Huffman.h"

int main(){
    string test = "ABRACADABRA!";
    cout<<"test string= "<<test<<endl<<endl;

    Huffman* hf = new Huffman();
    hf->compress(test);
    cout<<"after compressing:"<<endl;
    cout<<hf->encodeStr(test)<<endl;
    cout<<endl;

    cout<<"Trie Tree:"<<endl;
    for(int i=0;i<hf->getR();i++)
        if(hf->st[i]!="")
        cout<<(char)i<<" "<<hf->st[i]<<endl;

}


================================================
FILE: 5_Strings/Quick3String.h
================================================
#ifndef QUICK3STRING_H_INCLUDED
#define QUICK3STRING_H_INCLUDED

#include"func.h"
/*
字符串数组排序

LGD or MGD or quick3string 适用情况 P471
当字符串具有公共前缀时 三向快速排序更合适
quick3string 更加通用

note:
剩余15个字符可以使用插入排序
*/
class Quick3string{
private:
    int charAt(string s,int d){
        if(d==(int)s.size()) return -1;
        return s[d];
    }
    void swap(vector<string>& a,int i,int j){
        string tmp = a[i];
        a[i]=a[j];
        a[j]=tmp;
    }
    //高位优先形式 对dth位置字符三向切分
    void quick3string(vector<string>& a,int lo,int hi,int d){
        if(lo>= hi) return;
        int lt=lo;
        int gt=hi;
        int i=lo+1;
        int v=charAt(a[lo],d);
        while(i<=gt){
            int tmp = charAt(a[i],d);
            if(tmp < v) swap(a,lt++,i++);
            else if(tmp > v) swap(a,i,gt--);
            else i++;
        }

        //a[lo..lt-1] < v = a[lt..gt] < a[gt+1..hi].
        quick3string(a,lo,lt-1,d);
        if(v>=0) quick3string(a,lt,gt,d+1);
        quick3string(a,gt+1,hi,d);
    }
public:
    void vectorStrSort(vector<string>& a){
        quick3string(a,0,a.size()-1,0);
    }
};

#endif // QUICK3STRING_H_INCLUDED


================================================
FILE: 5_Strings/Quick3String_test.cpp
================================================
#include"Quick3string.h"
/*
字符串数组排序

LGD or MGD or quick3string 适用情况 P471
当字符串具有公共前缀时 三向快速排序更合适
quick3string 更加通用

note:
剩余15个字符可以使用插入排序
*/


int main(){
    vector<string> a;
    a.push_back("abb2");
    a.push_back("aab1");
    a.push_back("abb6");
    a.push_back("abc5");
    Quick3string* q3s = new Quick3string();
    q3s->vectorStrSort(a);

    for(auto i:a)
        cout<<i<<endl;
}


================================================
FILE: 5_Strings/README.md
================================================
# 字符串数组排序  
>低位优先  
缺点:  
字符串要求相同长度  
>高位优先  
> 三向快排排序  
思路:高位优先的,递归排序。之间相等部分去掉首字符继续递归  
note:  
大量具有公共前缀的字符串数组的排序  
  
//这两部分  我理解比较困难,实现复杂  
//我就跳过了  
# 单词查找树  
# 子串搜索   
   
# 正则表达式   
   
# 数据压缩   
只讨论无损压缩   
>Huffman编码   
已实现   
>LZW压缩   
我没看   


================================================
FILE: 6_Context/FlowEdge.h
================================================
#ifndef FLOWEDGE_H_INCLUDED
#define FLOWEDGE_H_INCLUDED

#include"func.h"
/*
maxFlow最大流问题
相比较无向图Edge,添加两个变量和两个API
*/

class FlowEdge{
private:
    int V;      //边的起点
    int W;
    double capacity;
    double flow;        //实际流量

public:
    FlowEdge():V(0),W(0),capacity(0.0){}
    FlowEdge(int v,int w,double c)
    :V(v),W(w),capacity(c),flow(0.0){}

    //边的剩余容量 传入参数是边的enpoint
    double residualCapacityTo(int vertex){
        if(vertex==V) return flow;      //backward edge
        else if(vertex==W) return capacity-flow;    //forward edge
        return (double)-1;
    }
    //增加流量 传入参数是边的终点
    void addResidualFlowTo(int vertex, double delta){
        if(vertex==V) flow -= delta;    //反向边
        else if(vertex==W) flow+=delta; //正向边
    }

    //其它API
    int from()const {return V;}
    int to()const {return W;}
    double getCapacity()const {return capacity;}
    double getFlow(){return flow;}
    int other(int vertex){
        if(vertex==V) return W;
        if(vertex==W) return V;
        return -1;
    }
    void setFlow(double delta){flow += delta;}
    bool operator==(const FlowEdge& that){return V==that.from() && W==that.to() && capacity==that.getCapacity();}
};

#endif // FLOWEDGE_H_INCLUDED


================================================
FILE: 6_Context/FlowFordFulkerson.h
================================================
#ifndef FLOWFORDFULKERSON_H_INCLUDED
#define FLOWFORDFULKERSON_H_INCLUDED
#include"FlowNetwork.h"
/*
Ford-Fulkerson方法
1.BFS判断剩余网络中是否存在
2.直到增广路径不存在

增广路径: 能从s到达t,路径上正向边不饱和而且反向边非零
*/

class FlowFordFulkerson{
private:
    vector<bool> marked;
    vector<FlowEdge> edgeTo;
    double totalVal;
    //BFS判断s到t是否存在增广路径
    bool hasAugmentingPath(FlowNetwork*G,int s,int t){
        edgeTo.assign(G->getV(),FlowEdge());
        marked.assign(G->getV(),false);
        queue<int> pq;
        pq.push(s);
        marked[s]=true;

        while(!pq.empty() && !marked[t]){
            int v = pq.front();
            pq.pop();
            for(FlowEdge e : G->getadj(v)){
                int w = e.other(v);
                //v->w边存在剩余容量则是非饱和边
                if(e.residualCapacityTo(w)>0 && !marked[w]){
                    edgeTo[w]=e;
                    marked[w]=true;
                    pq.push(w);
                }
            }
        }
        return marked[t];       //增广路径能否遍历到t
    }

public:
    FlowFordFulkerson(FlowNetwork* G){
        marked.resize(G->getV(),false);
        edgeTo.resize(G->getV());
        totalVal=0.0;
    }
    void calMaxFlow(FlowNetwork* G,int s,int t){
        totalVal = 0.0;
        while(hasAugmentingPath(G,s,t)){
            double delta = std::numeric_limits<double>::max();
            //edgeTo增广路径中的最小可增加的流量
            for(int v=t;v!=s;v=edgeTo[v].other(v)){
                delta = std::min(delta,edgeTo[v].residualCapacityTo(v));
            }
            //对于路径上每条边增加流量
            for(int v=t;v!=s;v=edgeTo[v].other(v)){
//                edgeTo[v].addResidualFlowTo(v,delta);         //由于java里面传递引用,需要C++稍作变化
                G->addResidualFlowTo(edgeTo[v],v,delta);
            }

            totalVal += delta;
        }
    }
    double getMaxFlow(){return totalVal;}
};

#endif // FLOWFORDFULKERSON_H_INCLUDED


================================================
FILE: 6_Context/FlowNetwork.h
================================================
#ifndef FLOWNETWORK_H_INCLUDED
#define FLOWNETWORK_H_INCLUDED
#include"FlowEdge.h"
/*
由FlowEdge构成的图 和无向图的结构相同
*/

class FlowNetwork{
private:
    int V;      //顶点个数
    int E;      //边的个数
    vector<vector<FlowEdge>> adj;
    void addEdge(int v,int w,double capacity){
        adj[v].push_back(FlowEdge(v,w,capacity));
        adj[w].push_back(FlowEdge(v,w,capacity));
    }

public:
    FlowNetwork(int v,int e)
    :V(v),E(e){
        adj.resize(v,vector<FlowEdge>());
    }
    FlowNetwork(string  file){
        std::ifstream infile(file);
        string tmp;
        int lineNum = 0;
        while(std::getline(infile,tmp)){
            std::istringstream iss(tmp);
            int v1,v2;
            double capacity;
            if(lineNum==0) {iss>>V; adj.resize(V,vector<FlowEdge>());}
            else if(lineNum==1) iss>>E;
            else {
                iss>>v1>>v2>>capacity;
//                cout<<v1<<" "<<v2<<" "<<capacity<<" "<<endl;
                addEdge(v1,v2,capacity);
            }
            lineNum++;
        }
    }

    //其他API
    int getV(){return V;}
    int getE(){return E;}
    vector<FlowEdge> getadj(int v){return adj[v];}
    void addResidualFlowTo(FlowEdge& e,int v,double delta){     //传入参数V是边的endPoint
        for(vector<FlowEdge>& i:adj){
            for(FlowEdge& j:i){
                if(j==e){
                    if(j.from()==v) j.setFlow(-delta);        //backward Edge
                    else if(j.to()==v) j.setFlow(delta);     //forward Edge
                }
            }
        }
    }
};


#endif // FLOWNETWORK_H_INCLUDED


================================================
FILE: 6_Context/README.md
================================================
# 事件驱动的粒子碰撞  
  
# B-树  
查找成本很低  需要空间大  
  
# 后缀数组  
字符串的子串中最长的公共前缀问题  
思路:  
排序的后缀数组,最长的公共前缀在相邻的位置出现  
  
# 最大流  
给定有向图找出满足平衡的最大流  
思路:  
剩余网络中不存在从S到T的增广路径  
(将增广路径所有边 add最小边的可增加容量)  

跳过   
# 归约问题  
# 不可解性   


================================================
FILE: 6_Context/SuffixArray.h
================================================
#ifndef SUFFIXARRAY_H_INCLUDED
#define SUFFIXARRAY_H_INCLUDED
#include"func.h"
#include"Quick3String.h"
//连续字符 子字符串
//非连续字符 子序列

/*
问题: string至少重复两次的最长子串
后缀数组
idea: sorted 后缀数组最长重复子串在相邻位置

API:
i 已排序的后缀数组的元素序号
1.select(i) 已排序的后缀数组第i元素
2.index(i) select(i)在原有的后缀数组序号
3.lcp(i) select(i)和select(i-1)的最长公共前缀长度
4.rank(string key) 小于key的字符串的数量
*/

class SuffixArray{
private:
    vector<string> suffixes;
    int N;
    int lcp(string str1,string str2){       //两个字符串的最长公共前缀
        int len = std::min(str1.size(),str2.size());
        for(int i=0;i<len;i++)
            if(str1[i]!=str2[i])
                return i;
        return len;
    }
public:
    //sorted 后缀数组
    SuffixArray(string str){
        N = str.size();
        suffixes.resize(N,"");
        for(int i=0;i<N;i++)
            suffixes[i]=str.substr(i);  //substr(i,N-i);
        Quick3string* q3s = new Quick3string();
        q3s->vectorStrSort(suffixes);
    }
    int lcp(int i){
        return lcp(suffixes[i],suffixes[i-1]);
    }
    //不断比较相邻的两个字符串的公共前缀长度
    string getLRS(){
        string longReaptedStr="";
        for(int i=1;i<(int)suffixes.size();i++){
            int len = lcp(i);
            //更新 lrs
            if((int)longReaptedStr.size() < len)
                longReaptedStr = suffixes[i].substr(0,len);
        }
        return longReaptedStr;
    }

    int rankSuffix(string key){
        //二分查找
        int lo=0;
        int hi=N-1;
        while(lo <= hi){
            int mid=lo+(hi-lo)/2;
            if(key == suffixes[mid])
                return mid;
            else if(key < suffixes[mid])
                hi = mid-1;
            else
                lo = mid+1;
        }
        return lo;
    }

    //其它API
    vector<string> getSuffix(){ return suffixes;}
    int length(){return N;}
    string select(int i){return suffixes[i];}
    int index(int i){return N-select(i).size();}

};

#endif // SUFFIXARRAY_H_INCLUDED


================================================
FILE: 6_Context/SuffixArray_test.cpp
================================================
    #include"SuffixArray.h"

    int main(){
        string test = "aacaagtttacaagc";
        string longReaptedStr = "";
        SuffixArray* sfa = new SuffixArray(test);

    //    for(auto i : sfa->getSuffix())
    //        cout<<i<<endl;

        //输出最长重复的子字符串
        cout<<sfa->getLRS()<<endl;
    }


================================================
FILE: README.md
================================================
# 使用说明  
本项目C++实现基础算法库,重构于Algorithm4th java代码  

e.g. 以插入排序为例  
```java
//1.添加算法所需头文件
#include"Insertion.h"

int main(){
    vector<int> test={5,4,-1,2,7};
//2. 调用算法
    Insertion::insort(test);
    for(auto i:test)
        cout<<i<<" "<<endl;
}
//3.其他算法使用样例 请查阅对应*_test.cpp文件
```
  
# 算法-头文件对应  
*基础*    
> 背包,队列,栈    
> 连通集   UnionFind.h      
    
*排序*   
> 初级排序  Insertion.h         
> 归并排序   
> 三向快速排序    Quick3way.h           
> 优先队列  HeapSort.h        
  
*查找*  
> 符号表    
> 二叉树   BinarySearchTree.h   
> 平衡二叉树 RedBlackTree.h     
> 散列表  
  
*图*    
> 无向图   Edge.h  Graph.h  
1.图连通集数量    DFSCC.h  
2.单点最短路径    BFSPath.h  
> 有向图    DiEdge.h    DiGraph.h  
1.环路判断  DFSDirectedCycle.h  
2.拓扑排序  DFSTopo.h  
> 最小生成树 DiEdge.h    EdgeWeightedGraph.h  
1.延时Prim算法  LazyPrimMST.h  
2.即时Prim算法  PrimMST.h    
3.Kruskal算法 KruskalMST.h  
>最短路径   DiEdge.h    EdgeWeightedDiGraph.h  
 1.Dijkstra算法   DijkstraSP.h  
 2.无环图Topo最长路径    TopoLongestPath.h  
 3.Bellman-Ford算法   BellmanFordSP.h  
  
*字符串*  
> 字符串数组排序    Quick3String.h  
> 单词查找树  
> 子串查找  
> 正则表达式  
> 数据压缩  Huffman.h  
    
*背景*    
> 粒子碰撞      
> B-树      
> 后缀数组  SuffixArray.h    
> 网络最大流问题 FlowEdge.h    FlowNetWork.h   FlowFordFulkerson.h    
> 归约问题  
> 不可解性  
  
# 引用  
*Algorithm 4th Edition*    
Author: Robert SedgeWick and Kevin Wayne  
[Website:](https://algs4.cs.princeton.edu/home/) https://algs4.cs.princeton.edu/home/  


================================================
FILE: func.h
================================================
#ifndef __FUNC_H__
#define __FUNC_H__

#include<string.h>
#include<stdio.h>
#include<iostream>
#include <fstream>
#include<string>
#include<set>
#include<stack>
#include<vector>
#include<sstream>
#include<queue>
#include<limits>
#include<map>
#include<unordered_map>
#include<hash_set>
#include <utility>
#include<algorithm>
using std::cout;
using std::endl;
using std::string;
using std::stack;
using std::vector;
using std::set;
using std::multiset;
using std::map;
using std::stringstream;
using std::unordered_map;
using std::queue;
using std::priority_queue;
#endif // __FUNC__