448. Find All Numbers Disappeared in an Array - LeetCode Solution

class Solution:
    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
        
        d = {}
        
        for i in range(len(nums)):
            if nums[i] in d:
                d[nums[i]] +=1
            else:
                d[nums[i]] = 1
        
        ans = []
        for i in range(1, len(nums)+1, 1):
            if i not in d:
                ans.append(i)
        
        return ans