238. Product of Array Except Self

Posted 2021-01-13 bernieloveslife

Given an array nums of n integers where n > 1, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

Example:

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

Note: Please solve it without division and in O(n).

Follow up:
Could you solve it with constant space complexity? (The output array does not count as extra space for the purpose of space complexity analysis.)

class Solution:
    def productExceptSelf(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
        """
        res = [1 for i in range(len(nums))]
        for i in range(1,len(nums)): #from left to right
            res[i] = res[i-1]*nums[i-1]
        # print(res)
        right = 1
        for i in range(len(nums)-2,-1,-1): #from right to left
            right *= nums[i+1]
            res[i] = res[i]*right
        return res