LeetCode in Kotlin

268. Missing Number

Easy

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.

Example 1:

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.

Example 2:

Input: nums = [0,1]

Output: 2

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

Example 3:

Input: nums = [9,6,4,2,3,5,7,0,1]

Output: 8

Explanation: n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.

Constraints:

Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?

Solution

class Solution {
    fun missingNumber(nums: IntArray): Int {
        var a = nums.size
        for (i in nums.indices) {
            a = a xor i
            a = a xor nums[i]
        }
        return a
    }
}