1148 Werewolf - Simple Version

Werewolf（狼人杀） is a game in which the players are partitioned into two parties: the werewolves and the human beings. Suppose that in a game,

player #1 said: “Player #2 is a werewolf.”;

player #2 said: “Player #3 is a human.”;

player #3 said: “Player #4 is a werewolf.”;

player #4 said: “Player #5 is a human.”; and

player #5 said: “Player #4 is a human.”.

Given that there were 2 werewolves among them, at least one but not all the werewolves were lying, and there were exactly 2 liars. Can you point out the werewolves?

Now you are asked to solve a harder version of this problem: given that there were N players, with 2 werewolves among them, at least one but not all the werewolves were lying, and there were exactly 2 liars. You are supposed to point out the werewolves.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (5≤N≤100). Then N lines follow and the i-th line gives the statement of the i-th player (1≤i≤N), which is represented by the index of the player with a positive sign for a human and a negative sign for a werewolf.

Output Specification:

If a solution exists, print in a line in ascending order the indices of the two werewolves. The numbers must be separated by exactly one space with no extra spaces at the beginning or the end of the line. If there are more than one solution, you must output the smallest solution sequence – that is, for two sequences A=a[1],…,a[M] and B=b[1],…,b[M], if there exists 0≤k<M such that a[i]=b[i] (i≤k) and a[k+1]<b[k+1], then A is said to be smaller than B. In case there is no solution, simply print No Solution.

Sample Input 1:

5
-2
+3
-4
+5
+4

Sample Output 1:

1 4

Sample Input 2:

6
+6
+3
+1
-5
-2
+4

Sample Output 2 (the solution is not unique):

1 5

Sample Input 3:

5
-2
-3
-4
-5
-1

Sample Output 3:

No Solution

题意

一局游戏中，有 N 个玩家，其中只有 2 个是狼人，并且 2 个狼人中有且只有 1 狼人说的是假话，全场一共只有 2 人说的是假话。

现在给定每个人用一个整数 x 来代表其发言情况，如果 x 大于 0 ，则该人说 x 是好人；反之如果 x 小于 0 ，则该人说 x 是狼人。

现在需要我们找到这组狼人并输出它们的编号，每个人的编号从 1 到 N ，如果答案不唯一，则输出最小序列解。

思路

由于本题数据量不大，所以我们可以用枚举的方法来做，先枚举这 N 个玩家中哪两个人是狼，再去判断当这两个人是狼的时候，是否满足题目的条件。如果满足则直接输出结果，否则继续往下枚举。

代码

#include<bits/stdc++.h>
using namespace std;
const int N = 110;
int q[N];
int n;
//如果说的假话返回1，说的真话返回0
int judge(int u, int i, int j)
{
    int t = q[u];
    //该人说t是好人
    if (t > 0)
    {
        if (t == i || t == j)  return 1;
        return 0;
    }
    //该人说t是狼人
    t = -t;
    if (t == i || t == j)  return 0;
    return 1;
}
int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)   cin >> q[i];
    //枚举所有狼人的可能性
    for (int i = 1; i <= n; i++)
        for (int j = i + 1; j <= n; j++)
        {
            //只能恰好有一个狼人说假话
            int s = judge(i, i, j) + judge(j, i, j);
            if (s != 1)    continue;
            //只能恰好有两个人说假话
            s = 0;
            for (int u = 1; u <= n; u++)
                s += judge(u, i, j);
            if (s != 2)    continue;
            //满足条件，直接输出答案
            cout << i << " " << j << endl;
            return 0;
        }
    //没有找到一个答案
    puts("No Solution");
    return 0;
}