匈牙利算法(二分图的最大匹配) -2025/11/6

匈牙利算法(二分图的最大匹配)

#include<bits/stdc++.h>
using namespace std;

const int N = 510, M = 100010;

int h[N], e[M], ne[M], idx;
int n1 , n2 ,m;
int match[N];
int st[N];
void add(int a,int b){
	e[idx] = b, ne[idx] = h[a], h[a] = idx ++;
}

bool find(int u){
	for(int i = h[u]; i != -1; i = ne[i]){
		int j = e[i];
		if(!st[j]){
			st[j] = 1;
			if(!match[j] || find(match[j])){
				match[j]  = u;
				return true;
			}
		}
	}
	return false;
}

int main(){
	ios::sync_with_stdio(false), cin.tie(0);
	
	memset(h , -1, sizeof h);
	
	cin >> n1 >> n2 >> m;
	while(m --){
		int a, b;
		cin >> a >> b;
		add(a, b);
	}
	int res = 0;
	for(int i = 1; i <= n1; i ++){
		memset(st, 0 , sizeof st);
		if(find(i)) res++;
	}
	cout << res << "\n";
	
	return 0;
}