Maximum Sum Subarray of Fixed Length

Given an array of integers and an integer \( k \), your task is to determine the maximum sum of any contiguous subarray of length \( k \). If there is no valid subarray (i.e., if \( k > n \) or \( k = 0 \)), output 0.

You are required to use an efficient sliding window technique to solve this problem. The sliding window method calculates the sum of the first \( k \) elements, and then slides the window by one element at a time, updating the sum by subtracting the element that is left behind and adding the new element.

The problem may include edge cases that need careful handling, such as when \( k \) is 0 or exceeds the length of the array.

inputFormat

The input is provided via STDIN in the following format:

• The first line contains an integer \( n \), which is the number of elements in the array.
• The second line contains \( n \) space-separated integers representing the array elements.
• The third line contains an integer \( k \), denoting the length of the subarray.

outputFormat

Output a single integer to STDOUT representing the maximum sum of any contiguous subarray of length \( k \). If no such subarray exists, output 0.

9
1 2 3 4 5 6 7 8 9
3

24