1166 Summit (25 分) PAT

A summit (峰会) is a meeting of heads of state or government. Arranging the rest areas for the summit is not a simple job. The ideal arrangement of one area is to invite those heads so that everyone is a direct friend of everyone.

Now given a set of tentative arrangements, your job is to tell the organizers whether or not each area is all set.

Input Specification:

Each input file contains one test case. For each case, the first line gives two positive integers N (≤ 200), the number of heads in the summit, and M, the number of friendship relations. Then M lines follow, each gives a pair of indices of the heads who are friends to each other. The heads are indexed from 1 to N.

Then there is another positive integer K (≤ 100), and K lines of tentative arrangement of rest areas follow, each first gives a positive number L (≤ N), then followed by a sequence of L distinct indices of the heads. All the numbers in a line are separated by a space.

Output Specification:

For each of the K areas, print in a line your advice in the following format:

if in this area everyone is a direct friend of everyone, and no friend is missing (that is, no one else is a direct friend of everyone in this area), print Area X is OK..
if in this area everyone is a direct friend of everyone, yet there are some other heads who may also be invited without breaking the ideal arrangement, print Area X may invite more people, such as H. where H is the smallest index of the head who may be invited.
if in this area the arrangement is not an ideal one, then print Area X needs help. so the host can provide some special service to help the heads get to know each other.

Here X is the index of an area, starting from 1 to K.

Sample Input:

8 10
5 6
7 8
6 4
3 6
4 5
2 3
8 2
2 7
5 3
3 4
6
4 5 4 3 6
3 2 8 7
2 2 3
1 1
2 4 6
3 3 2 1

Sample Output:

Area 1 is OK.
Area 2 is OK.
Area 3 is OK.
Area 4 is OK.
Area 5 may invite more people, such as 3.
Area 6 needs help.

实际上这是一个最大团问题，建立邻接矩阵，遍历即可。

代码如下：

#include <iostream>
#include <cstring>
#include <algorithm>using namespace std;const int N = 210;int vers[N];
bool g[N][N], st[N];
int n, m, k;bool check_friends(int l)
{for (int i = 0; i < l; i ++ )for (int j = 0; j < i; j ++ )if (!g[vers[i]][vers[j]])return false;return true;
}bool check_full_friends(int l, int& t)
{memset(st, 0, sizeof st);for (int i = 0; i < l; i ++ )st[vers[i]] = true;for (int i = 1; i <= n; i ++ )if (!st[i]){bool success = true;for (int j = 0; j < l; j ++ )if (!g[i][vers[j]]){success = false;break;}if (success) {t = i;return false;}}return true;
}int main()
{scanf("%d %d", &n, &m);for(int i = 1; i <= m; i ++ ){int a, b;scanf("%d %d", &a, &b);g[a][b] = g[b][a] = true;}scanf("%d", &k);for(int i = 1; i <= k; i ++ ){int l;scanf("%d", &l);for(int i = 0; i < l; i ++ ) scanf("%d", &vers[i]);if(check_friends(l)){int t = 1;if(check_full_friends(l, t)) printf("Area %d is OK.\n", i);else printf("Area %d may invite more people, such as %d.\n", i, t);}else printf("Area %d needs help.\n", i);}
}