[LeetCode] [136] Single Number Solution

 Problem Statement:

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one. You must implement a solution with a linear runtime complexity and use only constant extra space.


Example 1:

Input: nums = [2,2,1]

Output: 1

Example 2:

Input: nums = [4,1,2,1,2]

Output: 4

Example 3:

Input: nums = [1]

Output: 1


Brute-force Approach (JavaScript):

  • Create an object and store the digits in the array as key and the number of their occurrence as their value.
  • Iterate thru the object and if value of any key is equal to 1, return key as a Number.

Brute-force Solution:


Efficient Approach:
  • XOR or Exclusive OR has the following key properties:
    • x ^ x = 0
    • x ^ 0 = x

Efficient Solution:

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