268. Missing Number

Question

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Example1:

Input: nums = [3,0,1]
Output: 2
Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.

Algorithm

XOR can help us identify the only difference one in two different arrays. This is a trick.

Code

class Solution {
    public int missingNumber(int[] nums) {
        int n = 0;
        
        for (int num : nums) {
            n ^= num;
        }
        
        for (int i = 0; i < nums.length + 1; i++) {
            n ^= i;    
        }
        return n;
    }
}