POJ 1469 COURSES

 

匹配必须大于或者等于P，学生人数必须大于P。

CODE：

 

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
using namespace std;

const int MAXN = 310;
const int MAXM = 310*310;

int first[MAXN], xlink[MAXN], ylink[MAXN];
bool vis[MAXN];
int G[MAXN][MAXN];

int nx, ny;

void init()
{
    memset(G, 0, sizeof(G));
    memset(xlink, -1, sizeof(xlink));
    memset(ylink, -1, sizeof(ylink));
}

bool ED(int u)
{
    for(int v = 1; v <= ny; v++) if(G[u][v])
    {
        if(!vis[v])
        {
            vis[v] = 1;
            if(ylink[v] == -1 || ED(ylink[v]))
            {
                xlink[u] = v; ylink[v] = u;
                return true;
            }
        }
    }
    return false;
}

void solve()
{
    int ans = 0;
    if(ny < nx) { printf("NO\n"); return ;}
    for(int i = 1; i <= nx; i++)
    {
        if(xlink[i] == -1)
        {
            memset(vis, 0, sizeof(vis));
            ans += ED(i);
        }
    }
    printf(ans >= nx? "YES\n" : "NO\n");
}

void solve_case()
{
    int T;
    scanf("%d", &T);
    while(T--)
    {
        init();
        scanf("%d%d", &nx, &ny);
        for(int u = 1; u <= nx; u++)
        {
            int people;
            scanf("%d", &people);
            while(people--)
            {
                int v;
                scanf("%d", &v);
                G[u][v] = 1;
            }
        }
        solve();
    }
}

int main()
{
    solve_case();
    return 0;
}