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Problem

Submissions

Max Prefix

Contributed by

Tushar Gupta

Last Updated: 23 Feb, 2023

Easy

0/40

Avg time to solve 7 mins

Success Rate 90 %

2 upvotes

Problem Statement

You are given an array 'A' of length 'N'. You can perform the operation defined below any number of times (Possibly 0).

Choose 'l', 'r' (1 <= 'l' <= 'r' <='N') and reverse the subarray from 'l' to 'r'.

After that, Return the maximum possible sum of the prefix of this array of length 'K'.

For Example:-

Let 'N' = 5, 'K' = 3, 'A' = [4, 2, 1, 2, 2].
We can reverse the subarray from index 3 to 4 (1-based indexing).
Array becomes [4, 2, 2, 1, 2].
Our answer is 8.

Detailed explanation ( Input/output format, Notes, Images )

Input Format:-

First-line contains an integer 'T', which denotes the number of test cases.
For every test case:-
First-line contains two integers 'N' and 'K'.
Second-line contains 'N' space-separated integers, elements of array 'A'.

Output Format:-

For each test case, Return the maximum possible sum of the prefix of this array of length 'K'.

Note:-

You don’t need to print anything. Just implement the given function.

Constraints:-

1 <= 'T' <= 10
1 <= 'K' <= 'N' <= 10^5
1 <= 'A[i]' <= 10^3

The Sum of 'N' overall test cases does not exceed 10^5.
Time Limit: 1 sec

Sample Input 1:-

Sample Output 1:-

4
5

Explanation of sample input 1:-

First test case:-
We do not need to reverse any subarray.
Our answer is 4.

Second test case:-
We can reverse the subarray from index 1 to 3 (1-based indexing).
Array becomes [3, 2, 2].
Our answer is 5.

Sample Input 2:-

Sample Output 2:-

9
15

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