238 Product of Array Except Self.js

// Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

// Solve it without division and in O(n).

// For example, given [1,2,3,4], return [24,12,8,6].

// Follow up:
// Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)

/**
 * @param {number[]} nums
 * @return {number[]}
 */
 
// http://fisherlei.blogspot.com/2015/10/leetcode-product-of-array-except-self.html
var productExceptSelf = function(nums) {
    var len = nums.length;
    var output = Array(len).fill(1);
    var left = 1;
    var right = 1;
    
    for(var i = 0; i < len - 1; i++) {
        left *= nums[i];
        right *= nums[len - i - 1];
        output[i + 1] *= left;
        output[len - i - 2] *= right;
    }
    
    return output;
};