Question:

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

Example:

  1. Input:  [1,2,3,4]
  2. Output: [24,12,8,6]

Solution:

  1. /**
  2.  * @param {number[]} nums
  3.  * @return {number[]}
  4.  */
  5. var productExceptSelf = function(nums) {
  6.   const len = nums.length;
  7.   const result = new Array(len);
  8.   result.fill(1);
  10.   // 计算左边
  11.   for (let i = 1; i < len; i++) {
  12.     result[i] = result[i-1] * nums[i-1];
  13.   }
  15.   // 右边
  16.   for (let j = len - 2; j >= 0; j--) {
  17.     result[j] *= nums[j+1];
  18.     nums[j] *= nums[j+1];
  19.   }
  21.   return result;
  22. };

Runtime: 88 ms, faster than 78.80% of JavaScript online submissions for Product of Array Except Self.