PAT-2019年冬季考试-甲级 7-3 Summit

7-3 Summit (25分)

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.

Solution:

暴力即优雅

#include <bits/stdc++.h>
using namespace std;

const int maxn = 210;
const int inf = 0x3f3f3f3f;
bool g[maxn][maxn], vis[maxn];
int a[maxn];

inline const int read()
{
    int x = 0, f = 1; char ch = getchar();
    while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); }
    while (ch >= '0' && ch <= '9') { x = (x << 3) + (x << 1) + ch - '0'; ch = getchar(); }
    return x * f;
}

int main()
{
    int n = read(), m = read();
    while (m--)
    {
        int u = read(), v = read();
        g[u][v] = g[v][u] = true;
    }
    int t = read();
    for (int i = 1; i <= t; i++)
    {
        memset(vis, false, sizeof vis);
        printf("Area %d ", i);
        bool notFriend = false;
        int m = read(), minid = inf;
        for (int j = 0; j < m; j++)
        {
            a[j] = read();
            vis[a[j]] = true;
        }
        for (int j = 0; j < m; j++)
        {
            for (int k = j + 1; k < m; k++)
            {
                if (!g[a[j]][a[k]])
                {
                    notFriend = true;
                    break;
                }
            }
        }
        if (notFriend)
        {
            printf("needs help.\n");
            continue;
        }
        for (int j = 1; j <= n; j++)
        {
            bool noExtra = false;
            if (!vis[j])
            {
                for (int k = 0; k < m; k++)
                {
                    if (!g[j][a[k]])
                    {
                        noExtra = true;
                        break;
                    }
                }
                if (!noExtra) minid = min(minid, j);
            }
        }
        if (minid != inf) printf("may invite more people, such as %d.\n", minid);
        else printf("is OK.\n");
    }
    return 0;
}