My approach to solving LeetCode’s Running sum of 1d array code challenge.

Problem

Given an array nums. We define a running sum of an array as runningSum[i] = sum(nums[0]…nums[i]).

Return the running sum of nums.

Solution

We start by creating a new temporary array (temp) and populating it with the first array's element (nums[0]). We need to do this, as below we start for loop, where during each iteration, we will be using the last temporary array value (temp[i - 1]) and sum it with the current's loop value (nums[i]). We will push the result of this addition to the temp array.

Finally, we return the temp array.

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1var runningSum = function (nums) {
2  let temp = [nums[0]];
3
4  for (let i = 1; i < nums.length; i++) {
5    temp.push(temp[i - 1] + nums[i]);
6  }
7
8  return temp;
9};