hdu-5650 so easy(水题)

题目链接：

so easy

Time Limit: 2000/1000 MS (Java/Others)  

Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 138    Accepted Submission(s): 110

Problem Description

Given an array with

n

integers, assume f(S) as the result of executing xor operation among all the elements of set S. e.g. if S={1,2,3} then f(S)=0.

your task is: calculate xor of all f(s), here s⊆S.

 

Input

This problem has multi test cases. First line contains a single integer T(T≤20) which represents the number of test cases.
For each test case, the first line contains a single integer number n(1≤n≤1,000) that represents the size of the given set. then the following line consists of ndifferent integer numbers indicate elements(≤109) of the given set.

 

Output

For each test case, print a single integer as the answer.

 

Sample Input

1

3

1 2 3

 

Sample Output

0

In the sample，$S = \{1, 2, 3\}$, subsets of $S$ are: $\varnothing$, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}

题意：问一个集合的所有子集合的异或和的异或和;

思路：因为a^a=0;所以就看代码;

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const long long mod=1e9+;
int main()
{

    int t,n,a[];
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=;i<=n;i++)
        {
            scanf("%d",&a[i]);
        }
        if(n==)
        {
            cout<<a[]<<"\n";
        }
        else cout<<""<<"\n";
    }
    return ;
}