二分图匹配【模板】

传送门：

#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
#define ll long long
#define re register
const int N=1005;
inline void read(int &a)
{
    a=0;
    int d=1;
    char ch;
    while(ch=getchar(),ch>'9'||ch<'0')
        if(ch=='-')
            d=-1;
    a=ch^48;
    while(ch=getchar(),ch>='0'&&ch<='9')
        a=(a<<3)+(a<<1)+(ch^48);
    a*=d;
}
bool vis[N][N],book[N];
int mata[N],matb[N],n,m;
inline bool dfs(int u)
{
    for(re int i=1;i<=m;i++)
    {
        if(book[i]==0&&vis[u][i]==1)
        {
            book[i]=1;
            if(matb[i]==0||dfs(matb[i]))
            {
                matb[i]=u;
                mata[u]=i;
                return 1;
            }
        }
    }
    return 0;
}
int main()
{
    int e;
    read(n);
    read(m);
    read(e);
    for(re int i=1;i<=e;i++)
    {
        int a,b;
        read(a);
        read(b);
        if(a<1||b<1||a>n||b>m)
            continue;
        vis[a][b]=1;
        //vis[b][a]=1;
    }
    int ans=0;
    for(re int i=1;i<=n;i++)
    {
        memset(book,0,sizeof(book));
        ans+=dfs(i);
    }
    printf("%d",ans);
    return 0;
}