【POJ 1469】COURSES

#include <cstdio>
#include <cstring>

using namespace std;

int p, n, left[305];
bool g[105][305], v[305];

bool dfs(int x)
{
    for (int i = 1; i <= n; ++i)
        if (g[x][i] && v[i])
        {
            v[i] = false;
            if (left[i] == 0 || dfs(left[i]))
            {
                left[i] = x;
                return true;
            }
        }
    return false;
}

int main()
{
    int Test;
    scanf("%d", &Test);
    while (Test--)
    {
        scanf("%d%d", &p, &n);
        memset(g, false, sizeof(g));
        for (int i = 1; i <= p; ++i)
        {
            int num, x;
            scanf("%d", &num);
            while (num--)
            {
                scanf("%d", &x);
                g[i][x] = true;
            }
        }
        int ans = 0;
        memset(left, 0, sizeof(left));
        for (int i = 1; i <= p; ++i)
        {
            memset(v, true, sizeof(v));
            if (dfs(i)) ans++;
        }
        printf("%s\n", ans == p ? "YES" : "NO");
    }
    return 0;
}