Product of Array Except Self

Problem: 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

    def productExceptSelf(nums):
        import math
        if math.prod(nums) == 1:
            return nums
        res = []
        p = math.prod(nums)
        if p != 0:
            for i in range(len(nums)):
                res.append(p//nums[i])
        else:
            for i in range(len(nums)):
                res.append(math.prod(nums[:i] + nums[i+1:]))
        return res

Runtime: $O(n)$.

Back to String and Array Problems

---

anusha-murali.github.io