LeetCode 238. Product of Array Except Self (javascript solution)

Description:

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.

Solution:

Time Complexity : O(n)
Space Complexity: O(n)

var productExceptSelf = function(nums) {
    // Value to increment per each index
    let carry = 1
    // Array to return all the product values
    const output = Array(nums.length).fill(1)
    // Add products to output array starting at the front
    for(let i = 0; i < nums.length;i++){
        output[i]*=carry
        carry*=nums[i]
    }
    // Reset carry
    carry = 1
    // Add products to output array starting at the back
    for(let i = nums.length-1; i >= 0; i--){
        output[i]*=carry
        carry*=nums[i]
    }
    return output
};

Comments

[Siva Rama Krishna Bathula]

Brilliant soluton. absolutely loved it. My solution was about 70 lines, a little difficult to understand and is faster than only 10 % submissions and this one is just about 20 lines and so easy to understand and is faster than 70% submissions. I created an account here just to thank you for this.

[Jeremy Smith]

I get negative zeros for this, ie. does not pass test case:

Input: nums = [-1,1,0,-3,3]
Output: [0,0,9,0,0]