Leetcode 0448 Find All Numbers Disappeared in an Array

Problem statement

https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/

Solution

See similar Problems 0041: First Missing positive and 0442: Find All Duplicates in an Array. We an either swap elements, or use trick where we add n to all values of already found element. and then return indexes of elements which are <= n.

Complexity

Time complexity is O(n), additional space is O(1).

Code

class Solution:
    def findDisappearedNumbers(self, nums):
        n = len(nums)
        for num in nums:
            nums[(num-1) % n] += n
            
        return [i+1 for i in range(n) if nums[i] <= n]