# Product of Array Except Self

Category

Array / String

Checkbox

Checkbox

Difficulty

Medium

Index

7

Key Ideas

The key idea to solve the "Product of Array Except Self" problem is to use prefix sums to calculate the product of all numbers to the left and right of each element in the array, excluding the current element itself.

Problem Number

238

Problem Summary

The problem "Product of Array Except Self" (Problem Number 238) is a medium difficulty problem in the Array/String category. The task is to find an array where each element is the product of all the elements in the original array except itself. A key pitfall in solving this problem is handling the zero case, where a zero value in the input array can affect the product calculation.

Solution Summary

The best solution to solve the given problem is to use prefix sums. First, we initialize two arrays,

`prefixLeft`

and `prefixRight`

, both of size `n`

. Then, we iterate through the array from left to right and calculate the prefix sum of the elements, storing them in `prefixLeft`

. Next, we iterate through the array from right to left and calculate the prefix sum of the elements, storing them in `prefixRight`

. Finally, we iterate through the original array and calculate the product of the corresponding elements in `prefixLeft`

and `prefixRight`

, which gives us the product of array except self.Tags

Array

Prefix Sum