List the operations
Get, put, delete, sample, and expire imply different guarantees.
Data Structure Design
6 chapters · 10 challenges · The Architect's Citadel
Understand the idea, practise through play, then prove it in code. Choose your next quest below.
Visual introduction to this topic
Start here · 3 minute mental model
What is data structure design?
Design problems combine structures so every required operation meets a promised cost. The solution is an invariant shared by the components, not a collection of unrelated containers.
Think of a game service toolbox. A fast inventory might pair a map for direct lookup with a linked order for recent use. Each structure covers the other's weakness.
Route each operation through components that preserve one shared invariant.
Assign a cost budget
O(1) requirements usually need direct lookup plus another structure for order.
Maintain one invariant
Every mutation must update all structures atomically and consistently.
What you will learn firstThe Recent Cache
Begin the guided lesson Evict the least recently used key
01
LRU Cache
0/2 completePractice LRU cache through 2 visual expeditions.
02
Randomized Set
0/1 completePractice randomized set through 1 visual expedition.
03
Time Map
0/2 completePractice time map through 2 visual expeditions.
04
Stream Design
0/2 completePractice stream design through 3 visual expeditions.
05
Rate Tracking
0/2 completePractice rate tracking through 2 visual expeditions.
06
Final challenge
0/1 completeCombine the skills from this world in a final challenge.
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This track is checked against the sources below. Visual traces still carry their own complete or guided coverage label, so unfinished explanations are not presented as complete executions.