Missing Number Python

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?

// Using Extra space Hash set

class Solution:
    def missingNumber(self, nums: List[int]) -> int:
        seen_set = set(nums)
        for i in range(0,len(nums)+1):
            if i not in seen_set:
                return i



Time Complexity : O(n)
Space Complexity : O(n)