View Code of Problem 3929

#include<bits/stdc++.h>
using namespace std;

int main(){
	int T;
	cin>>T;
	while(T--){
		int n;
		int sum=0;
		cin>>n;//n个数
		int a[n];
		for(int i=0;i<n;i++){
			cin>>a[i];
		} 
		sort(a,a+n);
		for(int i=0;i<n;i++){
			int count=1;
			while(a[i+1]==a[i]){
				count++;
				i++;
			}
			if(count%2!=0){
				sum=sum^a[i];
			}
		}
		cout<<sum<<endl;
	}	
}