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Sliding Window•Pattern: Sliding Window•Medium

Longest subarray with sum ≤ k (all positives)

Problem Intuition & Objective

Find the maximum length subarray with sum at most k.

Time ComplexityO(n)
Optimal
Space ComplexityO(1)
Memory Bounds
Optimal Algorithmic Approach

Two-pointer sliding window for positive arrays.

Core Invariants & Edge Cases

  • Expand right pointer; when sum > k, shrink from left
  • For mixed-sign arrays, use prefix sums + sorted structure
  • Positive-only: two-pointer sliding window is O(n)
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