二分图最大匹配模板

//洛谷3386 
#include<bits/stdc++.h>
#define N 1005
using namespace std; 
int n,m,s,tot,ans;
int head[N],match[N];
bool vis[N];
inline int read(){
    int x=0,f=1; char ch=getchar();
    while (ch>'9'||ch<'0'){ if (ch=='-') f=-1; ch=getchar(); }
    while (ch<='9'&&ch>='0'){ x=(x<<3)+(x<<1)+ch-'0'; ch=getchar(); }
    return x*f;
}
struct node{
    int next,to;
}e[N*N];
void add(int x,int y){
    e[++tot].next=head[x];
    head[x]=tot;
    e[tot].to=y;
}
bool dfs(int u){
    for (int i=head[u];i;i=e[i].next){
        int v=e[i].to;
        if (vis[v]) continue;
        vis[v]=true;
        if (!match[v]||dfs(match[v])){
            match[v]=u;
            return true;
        }
    }
    return false;
} 
int main(){
    n=read(); m=read(); s=read(); 
    int x,y;
    for (int i=1;i<=s;i++){
        scanf("%d%d",&x,&y);
        if (x>n||y>m) continue;
        add(x,y);
    }
    for (int i=1;i<=n;i++){
        memset(vis,0,sizeof(vis));
        if (dfs(i)) ans++;
    }
    printf("%d
",ans);
    return 0;
}