Js - solving challenge Range Sum Query - Immutable with creating object and its properties

Question

I was going through the problems on leetcode site, and saw a problem that I don't know how to approach. This is how they explain it:

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Example: Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1 sumRange(2, 5) -> -1 sumRange(0, 5) -> -3 Note: You may assume that the array does not change. There are many calls to sumRange function.

And this is the code:

/**
 * @param {number[]} nums
 */
var NumArray = function(nums) {
   this.nums = nums;
};

/** 
 * @param {number} i 
 * @param {number} j
 * @return {number}
 */
NumArray.prototype.sumRange = function(i, j) {
    let sum = 0;
    for (i; i <= j; i++) {
        sum += this[i];
    }
    return sum;
};

/** 
 * Your NumArray object will be instantiated and called as such:
 * var obj = Object.create(NumArray).createNew(nums)
 * var param_1 = obj.sumRange(i,j)
 */

What I don't know how to do is, or what exactly it means is this part:

var obj = Object.create(NumArray).createNew(nums)

Am I suppose to create a property createNew that takes mums and creats and array, and why should I do that if the nums are already sent as an array?

My guess is that they messed up and meant `var obj = new NumArray(nums)`. — Bergi, Dec 07 '17 at 15:14
Can you state the full purpose of the exercise attached to this code? — M0nst3R, Dec 07 '17 at 15:16
Do you still need a solution for this problem? Have you already tried something? — M0nst3R, Dec 07 '17 at 15:31

Bergi · Accepted Answer · 2017-12-07T15:22:46.100

1

what exactly it means is this part:
var obj = Object.create(NumArray).createNew(nums)

They messed it up and meant simply var obj = new NumArray(nums) (which still is unnecessarily complicated for a functional language like JS).

Apparently the description was changed at some point by someone clueless, as all the old JavaScript submissions in the discussion section (e.g. this one) have the correct code in the comment.

edited Dec 07 '17 at 15:22

answered Dec 07 '17 at 15:20

Bergi

630,263
148
957
1,375

Thank you for noticing this. – Leff Dec 07 '17 at 15:21

Js - solving challenge Range Sum Query - Immutable with creating object and its properties

1 Answers1