【HDOJ】1455 Sticks

DFS。搜索以棍数为条件循环搜索较好，这样不会超时。

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>

 #define true  1
 #define false 0
 #define MAXN  70

 int alen;
 int parts[MAXN];
 char visit[MAXN];
 int n, m;

 int dfs(int beg, int cnt, int len) {
     int i;

     if (len == ) {
         ++cnt;
         if (cnt+ == m)
             return true;

         for (i=; i<n; ++i)
             if ( !visit[i] )
                 break;

         visit[i] = ;
         if ( dfs(i+, cnt, alen-parts[i]) )
             return true;
         visit[i] = ;

         return false;
     }

     for (i=beg; i<n; ++i) {
         if (visit[i] || parts[i]>len)
             continue;
         if (i && parts[i]==parts[i-] && !visit[i-])
             continue;
         visit[i] = ;
         if ( dfs(i+, cnt, len-parts[i]) )
             return true;
         visit[i] = ;
     }

     return false;
 }

 int comp(const void *a, const void *b) {
     return *(int *)b - *(int *)a;
 }

 int main() {
     int sum;
     int i;

     while (scanf("%d", &n)!=EOF && n) {
         sum = ;
         for (i=; i<n; ++i) {
             scanf("%d", &parts[i]);
             sum += parts[i];
         }
         qsort(parts, n, sizeof(int), comp);
         m = n+;
         while (m > ) {
             --m;
             if (sum%m)
                 continue;
             alen = sum/m;
             if (parts[] > alen)
                 continue;
             memset(visit, , sizeof(visit));
             if ( dfs(, , alen) )
                 break;
         }
         printf("%d\n", alen);
     }

     return ;
 }