HK二分图最大匹配算法模板

$ps:建图是核心，匹配都是一样的$

---

//hopcroft_karp算法，复杂度O(sqrt(n)*m)
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
const int N = 320;
const int INF = 0x3f3f3f3f;
struct edge
{
     
    int to, next;
}e[N*N];
int match[N], head[N];
bool used[N];
int p, n;
int nx, ny, cnt, dis; //nx,ny分别是左点集和右点集的点数
int dx[N], dy[N], cx[N], cy[N]; //dx,dy分别维护左点集和右点集的标号
//cx表示左点集中的点匹配的右点集中的点，cy正好相反
void add(int u,int v)
{
     
    e[cnt].to = v;
	e[cnt].next = head[u];
	head[u] = cnt++;
}
bool bfs() //寻找增广路径集，每次只寻找当前最短的增广路
{
     
    queue<int> que;
    dis = INF;
    memset(dx, -1, sizeof dx);
    memset(dy, -1, sizeof dy);
    for(int i = 1; i <= nx; i++)//将未遍历的节点入队，并初始化次节点距离为0
    if(cx[i] == -1) 
    {
     
    	que.push(i);
    	dx[i] = 0;
    }
    while(!que.empty())
    {
     
        int u = que.front();
		que.pop();
        if(dx[u] > dis) break;
        for(int i = head[u]; i != -1; i = e[i].next)
        {
     
            int v = e[i].to;
            if(dy[v] == -1)
            {
     
                dy[v] = dx[u] + 1;
                if(cy[v] == -1) dis = dy[v]; //找到了一条增广路，dis为增广路终点的标号
                else dx[cy[v]] = dy[v] + 1,que.push(cy[v]);
            }
        }
    }
    return dis != INF;
}
int dfs(int u)
{
     
    for(int i = head[u]; i != -1; i = e[i].next)
    {
     
        int v = e[i].to;
        if(! used[v] && dy[v] == dx[u] + 1) //如果该点没有被遍历过并且距离为上一节点+1
        {
     
            used[v] = true;
            if(cy[v] != -1 && dy[v] == dis) continue; //u已被匹配且已到所有存在的增广路终点的标号，再递归寻找也必无增广路，直接跳过
            if(cy[v] == -1 || dfs(cy[v]) )
            {
     
                cy[v] = u,cx[u] = v;
                return 1;
            }
        }
    }
    return 0;
}
int hopcroft_karp()
{
     
    int res = 0;
    memset(cx, -1, sizeof cx);
    memset(cy, -1, sizeof cy);
    while(bfs())
    {
     
        memset(used, 0, sizeof used);
        for(int i = 1; i <= nx; i++)
        if(cx[i] == -1)res += dfs(i);
    }
    return res;
}
int main()
{
     
    int t, a, b;
    scanf("%d", &t);
    while(t--)
    {
     
        cnt = 0;
        memset(head, -1, sizeof head);
        scanf("%d%d", &p, &n);
        for(int i = 1; i <= p; i++)
        {
     
            scanf("%d", &a);
            for(int j = 0; j < a; j++)
            {
     
                scanf("%d", &b);
                add(i, b);
            }
        }
        nx = p, ny = n;
        if(hopcroft_karp() == p) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}