All Repeating Except One

package pep.Day82;

public class All_Repeating_Except_One {
    public static void main(String[] args) {
        int arr[] = {2, 2, 1, 3, 3, 4, 4, 7, 9, 9, 7};
        int ans = 0;
        for (int x :
                arr) {
            ans = ans ^ x;
        }

        System.out.println(ans);
    }

}