DFS+剪枝。与HDOJ 1455如出一辙。

1 #include 
     
       2 #include 
      
        3 #include 
       
         4  5 #define MAXN 25 6  7 int nums[MAXN], n, len, cnt; 8 char visit[MAXN]; 9 10 int comp(const void *a, const void *b) {11     return *(int *)b - *(int *)a;12 }13 14 int dfs(int cnt, int beg, int l) {15     int i, flg = 0;16     if (cnt == 3)17         return 1;18     if (l == 0) {19         for (i=0; i
        
         >2;63             qsort(nums, n, sizeof(int), comp);64             memset(visit, 0, sizeof(visit));65             j = 1;66             for (i=0; i
         
           len) {68                     j = 0;69                     break;70                 }71             if (!j)72                 printf("no\n");73             else if ( dfs(0, 0, len) )74                 printf("yes\n");75             else76                 printf("no\n");77         }78     }79 80     return 0;81 }