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 longusing 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;}