1148 Werewolf

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). Then N lines follow and the i-th line gives the statement of the i-th player (1), 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 [ and [, if there exists 0 such that [ (i≤k) and [, 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：

　　有N个人，这里面有两只是狼人，一只狼人说真话，另一只狼人说假话，另外还有一个人类说假话，判断那两个人是狼人。

思路：

　　看大佬写的吧~

Code：

#include<iostream>
#include<vector>
#include<cmath>
#include<set>
#include<algorithm>

using namespace std;

bool cmp(pair<int, int> a, pair<int, int> b) {
    if (a.first == b.first) {
        return a.second < b.second;
    } else {
        return a.first < b.first;
    }
}

int main() {
    int n, t;
    cin >> n;

    set<int> human;
    set<int> werewolf;
    vector<int> said(n+1, 0);
    vector<pair<int, int> > twoWereWolf;

    for (int i = 1; i <= n; ++i) {
        cin >> t;
        said[i] = t;
    }

    bool wrong = false;
    int werewolf1, werewolf2;
    bool foundWerewolf1 = false;
    bool foundWerewolf2 = false;
    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= n; ++j) {
            if (j == i) continue;
            werewolf1 = -1;
            werewolf2 = -1;
            wrong = false;
            foundWerewolf1 = false;
            foundWerewolf2 = false;
            human.clear();
            werewolf.clear();
            for (int k = 1; k <= n; ++k) {
                if (k != i && k != j) {
                    if (said[k] < 0)
                        werewolf.insert(abs(said[k]));
                    else 
                        human.insert(said[k]);
                }
            }
            for (int h : human) {
                if (h == i) {
                    werewolf1 = j;
                    foundWerewolf1 = true;
                }
                if (h == j) {
                    werewolf1 = i;
                    foundWerewolf1 = true;
                }
            }
            for (int w : werewolf) {
                if (w != werewolf1) {
                    werewolf2 = w;
                    foundWerewolf2 = true;
                }
            }
            if (foundWerewolf1 && foundWerewolf2) {
                if (human.find(foundWerewolf1) == human.end() && human.find(foundWerewolf2) == human.end())
                    if (werewolf.find(werewolf1) != werewolf.end() || werewolf.find(werewolf2) != werewolf.end())
                        twoWereWolf.push_back({werewolf1, werewolf2});
            }
        }
    }

    sort(twoWereWolf.begin(), twoWereWolf.end(), cmp);

    if (twoWereWolf.size() > 0) {
        cout << twoWereWolf[0].first << " " << twoWereWolf[0].second << endl;
    } else {
        cout << "No Solution" << endl;
    }

    return 0;
}

记得上上次考试的时候我没有做出来这道题，今天又做了一下，只通过了两组样例。

---

大佬的代码：https://www.liuchuo.net/archives/6494

#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
int main() {
    int n;
    cin >> n;
    vector<int> v(n+1);
    for (int i = 1; i <= n; i++) cin >> v[i];
    for (int i = 1; i <= n; i++) {
        for (int j = i + 1; j <= n; j++) {
            vector<int> lie, a(n + 1, 1);
            a[i] = a[j] = -1;
            for (int k = 1; k <= n; k++)
                if (v[k] * a[abs(v[k])] < 0) lie.push_back(k);
            if (lie.size() == 2 && a[lie[0]] + a[lie[1]] == 0) {
                cout << i << " " << j;
                return 0;
            }
        }
    }
    cout << "No Solution";
    return 0;
}