Sliding window with frequency map.

Overview

Sliding window with frequency map.

Example 

  String s = "hello";
char[] chars = s.toCharArray();
// Process char array for O(1) access

Common Use Cases

  • Text processing
  • Parsing
  • Interview string problems

Pitfalls to Avoid

  • String concatenation in loops — use StringBuilder
  • Unicode vs ASCII assumptions
  • StringBuilder
  • Character arrays

Best Practices

  • Understand when to use minimum window substring versus simpler alternatives
  • Write unit tests covering edge cases and failure paths
  • Follow Java conventions and prefer standard library APIs when available
  • Profile before optimizing — measure impact in your specific workload