day_15.py

'''
Problem Statement:
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]
Constraint: It's guaranteed that the product of the elements of any prefix or suffix of the array (including the whole array) fits in a 32 bit integer.

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.)
'''
# Solution:

class Solution:
    def productExceptSelf(self, nums: List[int]) -> List[int]:

        size = len(nums)
        l = [1] * size
        r = [1] * size 
        for i in range(size - 1):
            l[i+1] = l[i] * nums[i]
    
        for i in range(size - 1, 0, -1):
            r[i - 1] = r[i] * nums[i]

        for i in range(size):
            l[i] *= r[i]
        return l