Max Subarray Sum

题面

在给定窗口大小 window_size 下，计算任意长度恰为 window_size 的连续子数组的最大和。

Implementation Requirements

• Use only native features (external libraries are not permitted)
• The solve function signature must remain unchanged
• 结果写入 output

Examples

[1,2,4,2,3], w=2 → 6
[-1,-4,-2,1], w=3 → -5

Constraints

• 1 ≤ N ≤ 50,000；-10 ≤ input[i] ≤ 10
• 1 ≤ window_size ≤ N
• Performance: N = 50,000