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Data Structures Core

26 problems·~14h·4 stages

The containers that make algorithms fast, implemented by hand. You will build stacks, queues, linked lists, heaps, tries, BSTs, union-find, and caches, then wire them into classic problems. Essential for interviews and for anyone who wants to know what a library really does.

Your progress

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Path readiness 0%Easy 0% · Medium 0% · Hard 0%

Continue path · Stack Push and Pop Simulation

What you will learn

  • Implement stacks, queues, and linked lists from scratch
  • Build heaps, hash maps, and caches layered on top
  • Code BSTs, tries, and range-query trees
  • Use union-find and monotonic stacks for classic problems

1Linear Structures

0/7

The containers everything else builds on: stack simulation, balanced brackets, postfix evaluation, a min stack, a queue built from two stacks, and linked-list traversal.

Stage checkpoint

0/2 to pass

A checkpoint is a short retrieval test drawn from this stage: solve 2 of 3 from memory to mark the stage complete. The stage stays open either way.

Tried this set and did not pass? Record it — the next set swaps in fresh problems from the same stage.
ProjectRecommended next stepBuild a Search EngineMedium

2Linked Lists and Heaps

0/6

Pointer surgery and priority order: merging sorted lists, heap parent/child indices, sift-up, heap push and pop, heapify, and the two-heap median finder.

Stage checkpoint

0/2 to pass

A checkpoint is a short retrieval test drawn from this stage: solve 2 of 3 from memory to mark the stage complete. The stage stays open either way.

Tried this set and did not pass? Record it — the next set swaps in fresh problems from the same stage.
ProjectRecommended next stepBuild a Search EngineMedium

3Hashing, Union-Find, and Caches

0/7

Hash-based and near-constant-time structures: string hashing, hash sets, separate chaining, union-find with path compression and union by rank, monotonic stacks, and an LRU cache.

Stage checkpoint

0/2 to pass

A checkpoint is a short retrieval test drawn from this stage: solve 2 of 3 from memory to mark the stage complete. The stage stays open either way.

Tried this set and did not pass? Record it — the next set swaps in fresh problems from the same stage.
ProjectRecommended next stepBuild a Search EngineMedium

4Trees and Tries

0/6

Hierarchical structures: trie insert/search/prefix, BST insert and preorder traversal, BST validation, level-order traversal, prefix collection, and segment-tree range sums.

Stage checkpoint

0/2 to pass

A checkpoint is a short retrieval test drawn from this stage: solve 2 of 3 from memory to mark the stage complete. The stage stays open either way.

Tried this set and did not pass? Record it — the next set swaps in fresh problems from the same stage.
ProjectRecommended next stepBuild a Search EngineMedium

Capstone

Collection

Close the path with one real artifact from the catalog.

Interview Prep Essentials

Two pointers, heaps, and graphs: the patterns built on this path that show up in real screens.