Cacher is the code snippet organizer for pro developers

/*
https://ideone.com/KmVVHQ
http://www.geeksforgeeks.org/find-the-number-occurring-odd-number-of-times/
*/

#include <iostream>
using namespace std;

int main() {
	// your code goes here
	int t, n;
	cin >> t;
	while(t--){
		cin >> n;
		int a[n];
		for(int i=0; i<n; i++)
			cin >> a[i];
		for(int i=0; i<n; i++){
			int count = 0;
			for(int j=0; j<n; j++){
				if(a[i] == a[j])
					count++;
			}
			if(count % 2 != 0){
				cout << a[i] << endl;
				break;
			}
		}
	}
	return 0;
}

/*
https://ideone.com/RQo8jN
http://www.geeksforgeeks.org/find-the-number-occurring-odd-number-of-times/
*/

#include <iostream>
using namespace std;

int main() {
	// your code goes here
	int t, n;
	cin >> t;
	while(t--){
		cin >> n;
		int a[n];
		for(int i=0; i<n; i++)
			cin >> a[i];
			
		int count[50] = {};
		for(int i=0; i<n; i++){
			count[a[i]]++;
		}
		for(int i=0; i<50; i++){
			if(count[i] % 2 != 0){
				cout << i << endl;
				break;
			}
				
		}
	}
	
	return 0;
}

/*
http://ideone.com/ZmW24e
http://www.geeksforgeeks.org/find-the-number-occurring-odd-number-of-times/
http://www.practice.geeksforgeeks.org/problem-page.php?pid=836
*/

#include <iostream>
using namespace std;

int main() {
	int t, n, x;
	cin >> t;
	while(t--){
		cin >> n;
		int odd = 0;
		while(n--){
			cin >> x;
			odd = odd ^ x;
		}
		cout << odd << endl;
	}
	return 0;
}