Pick from both sides!

Pick from both sides!¶

Created: February 28, 2022 10:26 AM
Link: https://www.interviewbit.com/problems/pick-from-both-sides/

Question:

Problem Description

Given an integer array A of size N.

You can pick B elements from either left or right end of the array A to get maximum sum.

Find and return this maximum possible sum.

NOTE: Suppose B = 4 and array A contains 10 elements then

• You can pick first four elements or can pick last four elements or can pick 1 from front and 3 from back etc . you need to return the maximum possible sum of elements you can pick.

Problem Constraints

1 <= N <= 105

1 <= B <= N

• 10 <= A[i] <= 10

  3

  3

Input Format

First argument is an integer array A.

Second argument is an integer B.

Output Format

Return an integer denoting the maximum possible sum of elements you picked.

Example Input

Input 1:

 A = [5, -2, 3 , 1, 2]
 B = 3

Input 2:

 A = [1, 2]
 B = 1

Example Output

Output 1:

 8

Output 2:

 2

Example Explanation

Explanation 1:

 Pick element 5 from front and element (1, 2) from back so we get 5 + 1 + 2 = 8

Explanation 2:

 Pick element 2 from end as this is the maximum we can get

Thoughts¶

We can think of it as a rotating range of max sum out of the 2xB numbers.