Topics
Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.
Example 1
Input: [3, 0, 1]
Output: 2
Example 2
Input: [9, 6, 4, 2, 3, 5, 7, 0, 1]
Output: 8
Note:
Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?