Creates an array that models a running sum

36th exercise - https://leetcode.com/problems/running-sum-of-1d-array/

runningSum.js

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+/*
+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.
+
+ 
+
+Example 1:
+
+Input: nums = [1,2,3,4]
+Output: [1,3,6,10]
+Explanation: Running sum is obtained as follows: [1, 1+2, 1+2+3, 1+2+3+4].
+Example 2:
+
+Input: nums = [1,1,1,1,1]
+Output: [1,2,3,4,5]
+Explanation: Running sum is obtained as follows: [1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1].
+Example 3:
+
+Input: nums = [3,1,2,10,1]
+Output: [3,4,6,16,17]
+*/
+
+//Answer//
+
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var runningSum = function(nums) {
+    return  nums.map((x,i)=>nums.slice(0,i+1).reduce((a, b) => a + b))
+};