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Array / Matrix•Pattern: Simulation / Boundary Shrinking•Medium

Spiral order traversal of a matrix

Problem Intuition & Objective

Traverse an m×n matrix in spiral (clockwise) order.

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

Boundary simulation: advance each boundary inward after completing each direction sweep.

Core Invariants & Edge Cases

  • Maintain four boundaries: top, bottom, left, right
  • Traverse right → down → left → up, shrinking boundaries after each direction
  • Stop when top > bottom or left > right
Previous ProblemFind all duplicates in an array (values in [1, n])Next Problem Rotate an n×n matrix in-place by 90°

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