leetcode#268 Missing Number

1. 문제

• https://leetcode.com/problems/missing-number/
  

2. 나의 풀이

class Solution:
    def missingNumber(self, nums: List[int]) -> int:
        count_book = {}
        for x in range(0, len(nums)+1):
            count_book[x] = 0
        
        for num in nums:
            count_book[num] += 1
        
        for key in count_book:
            if count_book[key] == 0:
                return key
        return null

Reference