Max Sum of Subarray with Constraints

Given an integer array `arr` and an integer `k`, find the maximum sum of any subarray of size at most `k`. A subarray is a contiguous part of an array. If the array is empty, return 0. Input Format: - The first line contains two integers, n (1 <= n <= 10^5) and k (1 <= k <= n). - The second line contains n space-separated integers representing the elements of the array, where each integer is in the range [1, 10^4]. Output Format: - Print the maximum sum of any subarray of size at most `k`. Example: Input: 5 3 1 2 3 4 5 Output: 12