DIY: Find Maximum Sum from Either End of an Array

Problem statement

For this challenge, you are given an array of integers, nums, and a positive integer, k. Your job is to find the maximum sum obtained from the k elements of the array. However, there is one condition: you cannot pick k elements at random. You can only remove elements one by one from either side of the array to add to the total sum.

The value of k will always be less than or equal to the length of the nums array.

Input

The inputs will be an array of integers called nums and a positive integer k. The following is an example of input:

[5,2,3,4,1,6,1]
3

Output

The output will be the maximum sum that can be obtained from k elements of the array by picking the elements from either side of the array one-by-one. The inputs mentioned-above will give the following output:

12

We obtained the output 12 because we picked out three numbers in the order: 5 (from the start), 1 (from the end), and 6 (from the end).

Coding exercise

You have to implement the max_sum(nums, k) method in the skeleton code given below.