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§ cs 201 · 6 guides

CS 201 — Data Structures

Stacks, queues, trees, heaps, tries, hashmaps — the containers every algorithm leans on, with implementations in Python and the problems that exercise them.

Level
6 guides
# Code Name Level Updated
1 —
Heap & Top-K Min/max heap for streaming top-K, kth smallest, and median-of-stream problems.
intermediate
2 —
In-Place Linked-List Reversal Three-pointer pattern that reverses a list, sublist, or every k nodes without extra memory.
beginner
3 —
Stack The cupboard you only reach into from the top — why one tiny rule gives you O(1) operations, order memory, and a quietly enormous family of solved problems.
beginner
4 —
Tree BFS / Level Order Queue-based traversal for level-by-level problems and shortest path in unweighted trees.
beginner
5 —
Tree DFS Recursive pre/in/post-order traversal — the foundation of most tree problems.
beginner
6 —
Trie Prefix tree for autocomplete, word search, and dictionary problems.
intermediate