Single Number

Given an array of integers, every element appears twice except for one. Find that single one.

Note:

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Solution:

public class Solution {
  public int singleNumber(int[] nums) {
    int ans = 0;
    for (int i = 0; i < nums.length; i++)
      ans ^= nums[i];
    return ans;
  }
}