[模板]二分图：匈牙利/增广路算法

int find(int k){
    for(int i=1;i<=n;i++)if(x[k][i]&&!al[i]){
        al[i]=1;
        if(bj[i]==0||find(bj[i])){
            bj[i]=k;return 1;
        }
    }
    return 0;
}
//in main
for(int i=1;i<=n;i++){
    memset(al,0,sizeof(al));
    if(find(i))ans++;
}