238-product_of_array_except_self.py

"""

https://leetcode.com/problems/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]
 

Constraints:
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.
 

Follow up: Can you solve the problem in O(1) extra space complexity? 
(The output array does not count as extra space for space complexity 
analysis.)

"""

def productExceptSelf(nums: list[int]) -> list[int]:
    zeros_count = nums.count(0)
    result = []

    if zeros_count < 1:
        total_product = 1
        for number in nums:
            total_product = total_product * number
        for number in nums:
            result.append(total_product // number)
    elif zeros_count == 1:
        total_product = 1
        for number in nums:
            if number != 0:
                total_product = total_product * number
        for number in nums:
            if number == 0:
                result.append(total_product)
            else:
                result.append(0)
    else:
        for number in nums:
            result.append(0)

    return result

if __name__ == '__main__':
    nums = [1,2,3,4]
    print(productExceptSelf(nums))