[uva] 10344 - 23 out of 5

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1285

这道题就比较单纯啦, 生成可重集的排列+dfs.

为了练习 我就不用stl了.

//
//  main.cpp
//  uva10344
//
//  Created by ello on 1/7/14.
//  Copyright (c) 2014 NextLife. All rights reserved.
//

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int gArr[5] = {0};
int gCopy[5] = {0};

bool dfs(int cur, int last) {
    if (cur == 4) {
        if (last == 23) {
            return true;
        }
        return false;
    }
    if (dfs(cur + 1, last + gCopy[cur + 1]) ||
        dfs(cur + 1, last - gCopy[cur + 1]) ||
        dfs(cur + 1, last * gCopy[cur + 1])) {
        return true;
    }
    return false;
}

bool solve(int cur) {
    if (cur == 5) {
        if (dfs(0, gCopy[0])) {
            return true;
        }
        return false;
    }
    for (int i = 0; i < 5; ++i) if (!i || gArr[i] != gArr[i - 1]) {
        int cnt1 = 0, cnt2 = 0;
        for (int j = 0; j < 5; ++j) if (gArr[j] == gArr[i]) cnt1 += 1;
        for (int j = 0; j < cur; ++j) if (gCopy[j] == gArr[i]) cnt2 += 1;
        if (cnt2 < cnt1) {
            gCopy[cur] = gArr[i];
            if (solve(cur + 1)) {
                return true;
            }
        }
    }
    return false;
}

int main(int argc, const char * argv[])
{
    while (scanf("%d%d%d%d%d", &gArr[0], &gArr[1], &gArr[2], &gArr[3], &gArr[4]) != EOF) {
        if (gArr[0] == 0) {
            break;
        }
        sort(gArr, gArr + 5);
        memcpy(gCopy, gArr, sizeof(gArr));
        if (solve(0)) {
            printf("Possible\n");
        } else {
            printf("Impossible\n");
        }
    }
    return 0;
}