hdoj 1455 Sticks 【dfs】

题意：找最短的木棍可以组成的长度，

hdoj  1518 的加强版

代码：

#include <stdio.h>
#include <string.h>
#include <algorithm>
using std::sort;
#define M 70
int s[M], vis[M];
int n, ans;
int cmp(int a, int b)
{
return a > b;
}
int dfs(int cou, int cur, int pos)
{
if(cou == n) return 1;
int i;
for(i = pos; i < n; i ++){
if(vis[i]) continue;
if(cur+s[i] < ans){
vis[i] = 1;
if(dfs(cou+1, cur+s[i], i+1)) return 1;
vis[i] = 0;
if(cur == 0) return 0;
while(s[i] == s[i+1]&&i+1<n) ++i;
}
else if(cur+s[i] == ans){
vis[i] = 1;
if(dfs(cou+1, 0, 0)) return 1;
vis[i] = 0;
return 0;
}
}
return 0;
}
int main()
{
int i, j;
while(scanf("%d", &n), n){
int sum = 0;
for(i = 0; i < n; i ++){
scanf("%d", &s[i]);
sum+=s[i];
}
sort(s, s+n, cmp);
for(i = n; i > 0; i --){
if(sum%i == 0&&(sum/i) >= s[0]){
ans = sum/i;
memset(vis, 0, sizeof(vis));
if(dfs(0, 0, 0)){
printf("%d\n", ans);
break;
}
}
}
}
return 0;
}