Product of Array Except Self

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.

You must write an algorithm that runs in O(n) time and without using the division operation.

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]

Solution

class Solution:
    def productExceptSelf(self, nums: List[int]) -> List[int]:
        l = [1] * (len(nums))
        prefix, postfix = 1, 1
        for i in range(len(nums)):
            l[i] = prefix
            prefix *= nums[i]
        for j in range(len(nums) - 1, -1, -1):
            l[j] *= postfix
            postfix *= nums[j]
        return l