[LeetCode] Find All Numbers Disappeared in an Array

🔍  문제

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.

Input: nums = [4,3,2,7,8,2,3,1]
Output: [5,6]

Input: nums = [1,1]
Output: [2]

Tip) The intuition behind using a hash map is pretty clear in this case

 

🖥  실행

1) Answer(Hash Table)

class Solution(object):
    def findDisappearedNumbers(self, nums):
        
        hash_table = {} #dict
        
        for num in nums:
            hash_table[num] = 1
        
        result = []    

        for num in range(1, len(nums) + 1):
            if num not in hash_table:
                result.append(num)
                
        return result

 

2) Better Solution(Space InPlace Modification Solution)

 

class Solution(object):
    def findDisappearedNumbers(self, nums):
        hash_table = {}
        
        for num in nums:
            hash_table[num] = 1
        
        result = []    
        
        for num in range(1, len(nums) + 1):
            if num not in hash_table:
                result.append(num)
                
        return result