136. Single Number

Given a non-empty 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?

Example 1:

Input: [2,2,1]
Output: 1

Example 2:

Input: [4,1,2,1,2]
Output: 4
  • xor
public int singleNumber(int[] nums) {
    int result = nums[0];
    for(int i = 1; i < nums.length; i++) result ^= nums[i];
    return result;
}