UVA - 10344 - 23 out of 5 （暴力）

23 out of 5

[code]#include <map>
#include <set>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <cstdio>
#include <cctype>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define INF 0x7fffffff
using namespace std;

int a[5];
int vis[5];

bool dfs(int n, int ans) {
    if(n >= 5) {
        if(ans == 23) return true;
        return false;
    }

    for(int i = 0; i < 5; i ++) {
        if(!vis[i]) {
            ans += a[i];
            vis[i] = 1;
            if(dfs(n + 1, ans)) return true;
            vis[i] = 0;
            ans -= a[i];

            ans -= a[i];
            vis[i] = 1;
            if(dfs(n + 1, ans)) return true;
            vis[i] = 0;
            ans += a[i];

            ans *= a[i];
            vis[i] = 1;
            if(dfs(n + 1, ans)) return true;
            vis[i] = 0;
            ans /= a[i];
        }
    }
    return false;
}

int main() {
    while(scanf("%d %d %d %d %d", &a[0], &a[1], &a[2], &a[3], &a[4]) != EOF) {
        if(a[0] == 0 && a[1] == 0 && a[2] == 0 && a[3] == 0 && a[4] == 0) break;

        memset(vis, 0, sizeof(vis));
        int flag = 0;

        for(int i = 0; i < 5; i ++) {
            vis[i] = 1;
            if(dfs(1, a[i])) {
                flag = 1;
                break;
            }
            vis[i] = 0;
        }

        if(flag == 1) {
            printf("Possible\n");
        }
        else printf("Impossible\n");    
    }
    return 0;
}