hdu 1258 从n个数中找和为t的组合 (DFS)

题意：首先给你一个t，然后是n，后面输入n个数，然后让你求的是n个数中和为t的序列总共有多少种，把他们按从左到右的顺序输出来。

Sample Input
4 6 4 3 2 2 1 1
5 3 2 1 1
400 12 50 50 50 50 50 50 25 25 25 25 25 25
0 0

Sample Output
Sums of 4:
4
3+1
2+2
2+1+1
Sums of 5:
NONE
Sums of 400:
50+50+50+50+50+50+25+25+25+25
50+50+50+50+50+25+25+25+25+25+25

 

 1 # include <cstdio>
 2 # include <cmath>
 3 # include <iostream>
 4 # include <cstring>
 5 # include <algorithm>
 6 using namespace std ;
 7 
 8 int a[20] ;
 9 int save[20] ;
10 int  n , t ;
11 bool flag ;
12 
13 bool cmp(const int &x , const int &y)
14 {
15     return x > y ;
16 }
17 
18 void dfs(int count , int L , int pos)
19 {
20     if (L > t)
21         return  ;
22     if (L == t)
23     {
24         for(int j=0;j<count-1;j++)
25         {
26             printf("%d+",save[j]);
27         }
28         printf("%d\n",save[count-1]);
29         flag = 1 ;
30         return  ;
31     }
32     for (int i = pos ; i < n ; i++)
33     {
34         save[count] = a[i] ;
35         dfs (count+1,L+a[i] , i+1) ;
36         while (a[i] == a[i+1])
37             i++ ;
38     }
39 
40 }
41 
42 int main()
43 {
44     //freopen("in.txt","r",stdin) ;
45 
46     while (scanf("%d %d" , &t , &n) != EOF)
47     {
48         if (t == 0 && n == 0)
49             break ;
50         int i ;
51         for (i = 0 ; i < n ; i++)
52         {
53             scanf("%d" , &a[i]) ;
54         }
55         sort(a,a+n,cmp) ;
56         flag = 0 ;
57         printf("Sums of %d:\n",t);
58         dfs(0,0,0) ;
59         if (flag == 0)
60         {
61             printf("NONE\n") ;
62         }
63     }
64 
65     return 0 ;
66 
67 }
View Code

 

posted @ 2015-05-16 15:21  __Meng  阅读(374)  评论(0)  编辑  收藏  举报