beingsde
Sign In
Back to all DSA patterns
String / Sliding Window•Pattern: Sliding Window•Medium

Minimum window substring containing all chars of T

Problem Intuition & Objective

Find the smallest window in S that contains every character in T.

Time ComplexityO(|S| + |T|)
Optimal
Space ComplexityO(|S| + |T|)
Memory Bounds
Optimal Algorithmic Approach

Two-pointer sliding window with frequency maps and a 'formed' count.

Core Invariants & Edge Cases

  • Maintain frequency maps for T and the current window
  • Expand right until all T chars are covered, then contract left
  • Track 'formed' counter to know when all required chars are present
Previous ProblemEncode and decode strings (no delimiter in charset)Next Problem Find all anagrams of P in S

System Design & Architecture Roadmap

Coding interviews are only 50% of the bar. Master High-Level Design, distributed systems, and Object-Oriented LLD.

60+ HLD QuestionsSharding, caching, and real-time distributed systems.27 LLD BlueprintsObject-oriented design patterns with class diagrams.SDE Quick ReferenceLatency numbers and database selection matrix.