匈牙利算法

#include<bits/stdc++.h>
using namespace std;
const int N = 550, M = 1e5 + 10;
int n1, n2, m, h[N], e[M], ne[M], idx;
int match[N], ans;
bool vis[N];

void addEdge(int f, int t)
{
    e[idx] = t, ne[idx] = h[f], h[f] = idx ++ ;
}

bool find(int u)
{
    for(int i = h[u]; ~i; i = ne[i])
    {
        int j = e[i];
        if(!vis[j])
        {
            vis[j] = true;
            if(!match[j] || find(match[j]))
            {
                match[j] = u;
                return true;
            }
        }
    }
    return false;
}

int main()
{
    cin >> n1 >> n2 >> m;
    memset(h, -1, sizeof h);
    for(int i = 0; i < m; i ++ )
    {
        int f, t;
        cin >> f >> t;
        addEdge(f, t);
    }

    for(int i = 1; i <= n1; i ++ )
    {
        memset(vis, false, sizeof vis);
        if(find(i)) ans ++ ;
    }

    cout << ans << endl;


    return 0;
}