so easy
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 617 Accepted Submission(s): 413
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
n
different 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}
Source
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题意：给出N个数的集合，这个集合的所有子集合的元素异或运算后，再将这些子集合的运算结果进行异或运算，问最后结果。
做这道题需要知道的是异或运算满足交换律（a^b)^(c^d)=a^b^c^d ,并且a^a=0; a^0=a;只有N为1时，集合中的元素只出现奇数次，其他情况集合中的元素都是出现偶数次，所以此时结果都为0；
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int main()
{
int t,i,j,k,l,m,n;
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
scanf("%d",&m);
for(i=1;i<n;i++)
scanf("%d",&k);
if(n==1)
printf("%d\n",m);
else
printf("0\n");
}
return 0;
}