二分图匹配（匈牙利算法）

/*    二分图匹配    匈牙利    by sbn*/#include<iostream>#include<cstdio>#include<cstring>using namespace std;bool map[1001][1001];int n1,n2,m;int flag[1001],vis[1001];bool dfs(int x){    for (int i1=1;i1<=n2;i1++){        if (map[x][i1]&&!vis[i1]){            vis[i1]=1;            if (flag[i1]==0||dfs(flag[i1])){                flag[i1]=x;                return true;            }        }    }    return false;}int main(){    cin>>n1>>n2>>m;    for (int i=1;i<=m;i++)    {        int a,b;        cin>>a>>b;        if (a<=n1&&b<=n2)        map[a][b]=1;    }    int ans=0;    for (int i=1;i<=n1;i++)        {        memset(vis,0,sizeof(vis));        if (dfs(i)) ans++;        }    cout<<ans<<endl;}