版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/polanwind/article/details/87891268
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <math.h>
#include <string>
#include <algorithm>
using namespace std;
int n, m;
bool vis[105];
int main() {
scanf("%d %d", &n, &m);
for (int i = 1;i <= n;++i) {
int a;
scanf("%d", &a);
for (int j = 1;j <= a;++j) {
int s;
scanf("%d", &s);
vis[s] = true;
}
}
bool flag = true;
for (int i = 1;i <= m;++i) {
if (vis[i] == false) {
flag = false;
}
}
if (flag) {
printf("YES\n");
}
else {
printf("NO\n");
}
return 0;
}