The Beauty Of XOR

The beauty of XOR is that it’s commutative and doing the same XOR twice cancels it out: 1 XOR 0 XOR 1 = 0. 1 XOR 1 XOR 0 = 0. The solution to this problem is to XOR all the integers together: Given an unsorted integer array, where every integer occurs twice except one, which occurs once, find the single integer.