[LeetCode] Product of Array Except Self

문제

Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].

The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.

예제

Example 1:

Input: nums = [1,2,3,4]
Output: [24,12,8,6]

Example 2:

Input: nums = [-1,1,0,-3,3]
Output: [0,0,9,0,0]

조건

• 2 <= nums.length <= $10^5$
• -30 <= nums[i] <= 30
• The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.

답

풀이 1

class Solution:
    def productExceptSelf(self, nums: List[int]) -> List[int]:
        answer1 = [1 for _ in range(len(nums))]
        answer2 = [1 for _ in range(len(nums))]
        
        for n in range(len(nums)-1):
            answer1[n+1] = answer1[n]*nums[n]
        for n in range(len(nums)-1,0,-1):
            answer2[n-1] = answer2[n]*nums[n]
            
        answer = [1 for _ in range(len(nums))]
        
        for n in range(len(nums)):
            answer[n] = answer1[n]*answer2[n]
        
        return answer