• 2336 Subset Sums

    时间限制 : 2000/1000 MS(Java/Others) | 内存限制 : 131072/65536 KB(Java/Others)

    提交数 : 23 | 通过数 : 5

    题目描述

    For many sets of consecutive integers from 1 through N (1 <= N <= 39), one can partition the set into two sets whose sums are identical. 
    
    For example, if N=3, one can partition the set {1, 2, 3} in one way so that the sums of both subsets are identical: 
    
    {3} and {1,2} 
    This counts as a single partitioning (i.e., reversing the order counts as the same partitioning and thus does not increase the count of partitions). 
    
    If N=7, there are four ways to partition the set {1, 2, 3, ... 7} so that each partition has the same sum: 
    
    {1,6,7} and {2,3,4,5} 
    {2,5,7} and {1,3,4,6} 
    {3,4,7} and {1,2,5,6} 
    {1,2,4,7} and {3,5,6} 
    Given N, your program should print the number of ways a set containing the integers from 1 through N can be partitioned into two sets whose sums are identical. Print 0 if there are no such ways. 
    
    Your program must calculate the answer, not look it up from a table.

    输入要求

    There are muiltply cases;
    One case contains a single line with a single integer representing N, as above.

    输出要求

    The Output  contains a single line with a single integer that tells how many same-sum partitions can be made from the set {1, 2, ..., N}. The output file should contain 0 if there are no ways to make a same-sum partition.

    输入样例

    7
    

    输出样例

    4
    

    提示


    来源

    USACO

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