ACM二分图匹配和匈牙利算法

算法:ACM二分图匹配 HDU2063

题目地址：http://acm.hdu.edu.cn/showproblem.php?pid=2063

摘录于互联网，原创作者redraiment，很详细的二分图匹配入门资料！

#include <stack>

#include <cstdio>

#include <cstring>

#include <iostream>

using namespace std;

typedef struct node {

    int ord;

    node * next;

}Node;

const int size = 512 + 1;

Node    list[size];

int    X[size];

int    Y[size];

bool    visit[size];

int    size_x;

int    size_y;

stack    <int>    stk;

void init() {

    int    i;

    for (i = 1; i <= size_x; i++)

        list[i].next = NULL;

    memset(X, 0, (size_x + 1) * sizeof(int));

    memset(Y, 0, (size_y + 1) * sizeof(int));

}

void input(int len) {

    int    i;

    int    x;

    int    y;

    Node*    p;

    for (i = 0; i < len; i++)

    {

        scanf("%d%d", &x, &y);

        p = new Node;  

       p->ord = y;   

      p->next = list[x].next;   

      list[x].next = p;

    }

}

bool dfs(int x) {

    Node*    p;

    stk.push(x);

    for (p = list[x].next; p; p = p->next)

    {

        if (!visit[p->ord])

        {

            visit[p->ord] = true;

            stk.push(p->ord);

            if (!Y[p->ord] || dfs(Y[p->ord]))

                return true;

            else

                stk.pop();

        }

    }

    stk.pop();

    return false;

}

void solve() {

    int    i;

    int    top;

    for (i = 1; i <= size_x; i++)

    {

        while (!stk.empty()) stk.pop();

        memset(visit, false, size_y + 1);

        if (dfs(i))

        {

            while (!stk.empty())

            {

                top = stk.top();

                stk.pop();

                Y[top] = stk.top();

                X[stk.top()] = top;

                stk.pop();

            }

        }

    }

}

void output()

{

    int    i;

    int    count = 0;

    Node*    p;

    for (i = 1; i <= size_x; i++)

    {

        if (X[i]) count++;  

       while (p = list[i].next)

        {

            list[i].next = p->next;

            delete p;

        }

    }

    cout << count << endl;

}

int main(void) {

    int    n;

    while (scanf("%d", &n), n)

    {

        scanf("%d%d", &size_x, &size_y);

        init();

        input(n);

        solve();

        output();

        while (!stk.empty()) stk.pop();

    }

    return 0;

}