uva 307

排序之后再剪枝，有点神

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <map>
#include <set>
#include <sstream>
#include <string>
#include <cstring>
#include <algorithm>
#include <iostream>
#define maxn 200010
#define INF 0x7fffffff
#define inf 10000000
#define ull unsigned long long
#define ll long long
using namespace std;

int a[65], n;
bool vis[65];
bool cmp(int a, int b)
{
    return a > b;
}
bool dfs(int cc, int now, int aim, int k, int cur)
{
   // printf("*****%d***%d***\n", now, cur);
    if(cur == cc) return true;
    for(int i = k; i < n; ++ i)
    {
        //if(i && !vis[i-1] && a[i] == a[i-1]) continue;
        if(!vis[i] && a[i] < now)
        {
            vis[i] = 1;
            if(dfs(cc, now-a[i], aim, i+1, cur)) return true;
            vis[i] = 0;
            if(now == aim)                       //第一个棒如果用不到，显然不能成功，直接结束
                return false;                
        }
        else if(!vis[i] && a[i] == now)
        {
            vis[i] = 1;
            if(dfs(cc, aim, aim, 0, cur+1)) return true;
            vis[i] = 0;
            return false;                        //因为棒从大到小排，如果无法成功，直接结束
        }
    }
    return false;
}
int main()
{
    while(scanf("%d", &n) == 1 && n)
    {
        int _max = 0, sum = 0, ans;
        memset(vis, 0, sizeof(vis));
        for(int i = 0; i < n; ++ i)
        {
            scanf("%d", &a[i]);
            _max = max(_max, a[i]);
            sum += a[i];
        }
        sort(a, a+n, cmp);
        for(int i = _max; i <= sum; ++ i)
        {
            if(sum%i == 0 && dfs(sum/i - 1, i, i, 0, 0))
            {
                ans = i;
                break;
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}