Longest Subarray

Problem Overview

• Find the maximum length of a contiguous subarray whose sum is less than or equal to k.
• Input: integer array a and integer k; Output: an integer length.
• Constraints: n up to 1e5, a[i] in 1–1e3, k up to 1e9; performance matters for large data.
• Real-world domain: array/window sum evaluation; a common coding interview problem and interview question from Goldman interviews.