Leetcode 268. Missing Number. Python [O(n) vs O(1)]

268. Missing Number

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.

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.

class Solution:

def missingNumber(self, n: List[int]) -> int:

#[3,0,1]

ans = len(n) #3

for i in range(len(n)): # 0 1 2

ans += (i - n[i]) # -3 1 1

return ans # 3 - 1 = 2

Explaination :

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