238. Product of Array Except Self

• categories: Code, Interview Question, leetcode, Medium
• source: https://leetcode.com/problems/product-of-array-except-self
• topics: Array

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.

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