Element that appears once where every element occurs twice

PROBLEM :

Given an array of integers, every element appears twice except for one. Find that single one in linear time complexity and without using extra memory.

Input:
The first line of input consists number of the test cases. The description of T test cases is as follows:
The first line of each test case contains the size of the array, and the second line has the elements of the array.

Output:
In each separate line print the number that appears only once in the array.

Constraints:
1 = T = 70
1 = N = 100
0 = A[i] = 100000


Example:
Input:
1
11
1 2 4 3 3 2 5 6 1 6 5

Output:
4
   
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SIMPLE c++ IMPLEMENTATION :
--------------------------------------------------------------------------------

#include<iostream>
using namespace std;
int main()
{
    int t ;
    cin>>t ;
    while(t--){
        int no ;
        cin>>no ;
       
        int arr[no] ;
        for(int i=0;i<no;i++)
            cin>>arr[i] ;
           
        int temp=0 ;
        for(int i=0;i<no;i++)
            temp=temp^arr[i] ;
           
        cout<<temp<<endl ;
    }
return 0;
}

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