Prefix tree (Trie) data structure and string-based problems.

• Trie node structure
• Insert, search, and prefix operations
• Word dictionary problems
• Autocomplete systems
• Longest common prefix
• Word search in matrix
• XOR maximum problems using binary trie

• Trie excels at prefix-based queries
• Each node typically has 26 children (for lowercase letters)
• Space-time tradeoff: uses more space for faster queries
• isEnd flag marks complete words
• Useful for dictionary operations and string matching