Problem

At Stripe, a service emits every integer from 0 to n exactly once, but one value is missing from the final array. Given an array nums containing n distinct integers in the range [0, n], return the missing number.

Formal Specification

• Input: An array of integers nums
• Output: An integer representing the single missing value in the range [0, n]
• len(nums) = n
• All values in nums are distinct
• Each value is in the inclusive range [0, n]

Examples

Example 1

• Input: nums = [3, 0, 1]
• Output: 2
• Explanation: The numbers should be 0, 1, 2, 3, so 2 is missing.

Example 2

• Input: nums = [0, 1]
• Output: 2
• Explanation: The full range is 0, 1, 2, and 2 does not appear.

Example 3

• Input: nums = [9, 6, 4, 2, 3, 5, 7, 0, 1]
• Output: 8
• Explanation: Every number from 0 to 9 appears except 8.

Constraints

• 1 <= len(nums) <= 10^5
• 0 <= nums[i] <= len(nums)
• All integers in nums are unique
• Exactly one number in the range [0, n] is missing