Geeksforgeeks Solution For " Element that appears once where every element occurs twice "

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Problem :-  Element that appears once where every element occurs twice

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Solution :- 

#include <iostream>
using namespace std;

int appearance(int a[],int n){
    int res=a[0];
    //int bit_mask;
    for(int i=1; i<n; i++){
        res=res^a[i];
    }
    return res;
}

int main() {
int t;
cin>>t;
while(t--){
   int n;
   cin>>n;
   int a[n];
   for(int i=0;i<n;i++)
       cin>>a[i];
   cout<<appearance(a,n)<<endl;
   
}
return 0;
}

Output:-

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