poj 1011 Sticks

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 69843		Accepted: 15257

本题对本人来说有点小难啊，交了n次都是tle后来看了别人的代码才知道加了一句剪枝，但这一句话是什么意思，我到现在也没看懂，如果哪位大牛看到此随笔，麻烦给我也解释一下。能举出例子最好！

代码：

 

  
    

   
     
   
      1 
   
     #include
   
     <
   
     stdio.h
   
     >
   
     

   
      2 
   
     #include
   
     <
   
     string
   
     .h
   
     >
   
     

   
      3 
   
     #include
   
     <
   
     stdlib.h
   
     >
   
     

   
      4 
   
      
   
     int
   
      n,used[
   
     100
   
     ],sticks[
   
     100
   
     ];

   
      5 
   
      
   
     int
   
      compare(
   
     const
   
      
   
     void
   
      
   
     *
   
     a,
   
     const
   
      
   
     void
   
      
   
     *
   
     b)

   
      6 
   
     {

   
      7 
   
      
   
     return
   
      
   
     *
   
     (
   
     int
   
      
   
     *
   
     )b
   
     -*
   
     (
   
     int
   
      
   
     *
   
     )a;

   
      8 
   
     };

   
      9 
   
     
   
     int
   
      test(
   
     int
   
      unused,
   
     int
   
      left,
   
     int
   
      len)

   
     10 
   
     {

   
     11 
   
      
   
     int
   
      i;

   
     12 
   
      
   
     if
   
     (unused
   
     ==
   
     0
   
      
   
     &&
   
      left
   
     ==
   
     0
   
     )

   
     13 
   
      
   
     return
   
      
   
     1
   
     ;

   
     14 
   
      
   
     if
   
     (left
   
     ==
   
     0
   
     )

   
     15 
   
      left
   
     =
   
     len;

   
     16 
   
      
   
     for
   
     (i
   
     =
   
     1
   
     ;i
   
     <=
   
     n;i
   
     ++
   
     )

   
     17 
   
      {

   
     18 
   
      
   
     if
   
     (used[i])

   
     19 
   
      
   
     continue
   
     ;

   
     20 
   
      
   
     if
   
     (sticks[i]
   
     >
   
     left)

   
     21 
   
      
   
     continue
   
     ;

   
     22 
   
      used[i]
   
     =
   
     1
   
     ;

   
     23 
   
      
   
     if
   
     (test(unused
   
     -
   
     1
   
     ,left
   
     -
   
     sticks[i],len))

   
     24 
   
      
   
     return
   
      
   
     1
   
     ;

   
     25 
   
      used[i]
   
     =
   
     0
   
     ;

   
     26 
   
      
   
     if
   
     (sticks[i]
   
     ==
   
     left 
   
     ||
   
      left
   
     ==
   
     len)

   
     27 
   
      
   
     break
   
     ;

   
     28 
   
      }

   
     29 
   
      
   
     return
   
      
   
     0
   
     ;

   
     30 
   
     }

   
     31 
   
     
   
     int
   
      main()

   
     32 
   
     {

   
     33 
   
      
   
     int
   
      i,max,sum;

   
     34 
   
      
   
     while
   
     (scanf(
   
     "
   
     %d
   
     "
   
     ,
   
     &
   
     n)
   
     !=
   
     EOF)

   
     35 
   
      {

   
     36 
   
      
   
     if
   
     (n
   
     ==
   
     0
   
     )

   
     37 
   
      
   
     break
   
     ;

   
     38 
   
      max
   
     =
   
     0
   
     ;sum
   
     =
   
     0
   
     ;

   
     39 
   
      
   
     for
   
     (i
   
     =
   
     1
   
     ;i
   
     <=
   
     n;i
   
     ++
   
     )

   
     40 
   
      {

   
     41 
   
      used[i]
   
     =
   
     0
   
     ;

   
     42 
   
      scanf(
   
     "
   
     %d
   
     "
   
     ,
   
     &
   
     sticks[i]);

   
     43 
   
      sum
   
     +=
   
     sticks[i];

   
     44 
   
      }

   
     45 
   
      qsort(sticks
   
     +
   
     1
   
     ,n,
   
     sizeof
   
     (sticks[
   
     0
   
     ]),compare);

   
     46 
   
      max
   
     =
   
     sticks[
   
     1
   
     ];

   
     47 
   
      
   
     for
   
     (i
   
     =
   
     max;i
   
     <=
   
     sum;i
   
     ++
   
     )

   
     48 
   
      {

   
     49 
   
      
   
     if
   
     (sum
   
     %
   
     i
   
     !=
   
     0
   
     )

   
     50 
   
      
   
     continue
   
     ;

   
     51 
   
      
   
     if
   
     (test(n,i,i))

   
     52 
   
      {

   
     53 
   
      printf(
   
     "
   
     %d\n
   
     "
   
     ,i);

   
     54 
   
      
   
     break
   
     ;

   
     55 
   
      }

   
     56 
   
      }

   
     57 
   
      }

   
     58 
   
      
   
     return
   
      
   
     0
   
     ;

   
     59 
   
     }

   
     60 
   
     

   
     61