Fixed-Length Subarray Maximum Sum

You are given an array of n integers and a positive integer k. Your task is to compute the maximum sum of any contiguous subarray of length k. Specifically, if the array is denoted as \(a_1, a_2, \dots, a_n\), you need to find \(\max_{1 \leq i \leq n-k+1} \sum_{j=i}^{i+k-1} a_j\).

If \(n < k\), output 0. This problem requires a sliding window approach to efficiently compute subarray sums.

inputFormat

The first line contains two integers n and k, where n is the number of elements in the array and k is the length of the contiguous subarray to consider. The second line contains n space-separated integers representing the array.

Input Format:

n k
a1 a2 a3 ... an

outputFormat

Output a single integer — the maximum sum of any contiguous subarray with length k. If n < k, output 0.

Output Format:

max_sum

6 3
2 1 5 1 3 2

9