dsa7 min read
Serialize and Deserialize Binary Tree — BFS Queue Encoding
Solve LeetCode 297 Serialize and Deserialize Binary Tree with a BFS queue producing a level-order encoding parsed in O(n). A FAANG hard tree design favorite.
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dsa7 min read
Trapping Rain Water — Monotonic Stack Layered Fill
Solve LeetCode 42 Trapping Rain Water in O(n) using a monotonic decreasing stack to fill water layer by layer. The signature FAANG monotonic stack hard problem.
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dsa7 min read
Stacks and Queues Master Recap — All Patterns, Templates, and Interview Cheatsheet
A printable cheatsheet for the entire Stacks and Queues category — seven patterns, ready-to-paste templates, Big-O reference, and a MAANG priority order.
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dsa9 min read
String Algorithms Complete Guide — KMP, Z, Rolling Hash, Suffix Array, Manacher
Master every advanced string algorithm asked in FAANG interviews — KMP failure function, Z-array, Rabin-Karp rolling hash, suffix arrays, Manacher palindromes, and Aho-Corasick.
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dsa10 min read
Z Algorithm Explained — Linear Time Pattern Matching with the Z Array
The Z algorithm computes Z[i] equals the length of the longest substring starting at index i that matches a prefix of the string in linear O(n) time. Cleaner than KMP for many problems and the foundation of competitive programming string toolkits.
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