448 Find All Numbers Disappeared in an Array

1. Description

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums.

 

constraints :

• n == nums.length
• 1 <= n <= \(10^{5}\)
• 1 <= nums[i] <= n

2. Algorithms

1. Start
2. Store the length of input nums into variable name "n".
3. Declare set data structure named all_nums. This variable will store all integers range in 1 to n.
4. Make set from input nums.
5. Calculate difference between all_nums and nums, and return the difference in list.
6. End

3. Codes

class Solution:
    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
        n = len(nums)
        all_nums = set(range(1, n+1))
        nums = set(nums)
        
        return all_nums - nums

4. Conclusion