Leetcode 268. Missing Number

Problem

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.

Algorithm

Sum all the numbers as $x$ and use $\frac{n(n+1)}{2}-x$.

Code

class Solution:def missingNumber(self, nums: List[int]) -> int:sum_, n_ = 0, len(nums)for num in nums:sum_ += numreturn n_ * (n_ + 1) // 2 - sum_