Structure is a promise
Arrays promise direct indexing; maps promise lookup by key; trees promise hierarchy.
The Algorithmic Compass
6 chapters · 6 challenges · The Cartographer's Camp
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 are data structures and algorithms?
A data structure is a way to organize information so particular operations become easy. An algorithm is the repeatable sequence of decisions that uses that structure to produce an answer.
Think of a game inventory. The same items could live in a quick-access belt, a sorted chest, or a map keyed by name. The best container depends on what the player needs to do next.
Choose the operations first; the right structure follows.
Algorithms spend operations
Count reads, writes, comparisons, and memory instead of trusting machine speed.
Constraints choose the tool
Input size and required operations rule out solutions before coding begins.
What you will learn firstWhat Is a Data Structure?
Begin the guided lesson Start here · organize information with a purpose
01
Start Here
0/1 completeUnderstand what a data structure is before choosing algorithms.
02
Measuring Work
0/1 completeCount operations and connect them to input size.
03
Growth Rates
0/1 completeCompare constant, logarithmic, linear, and faster growth.
04
Nested Work
0/1 completeRecognize quadratic, cubic, and dominant terms.
05
Memory
0/1 completeMeasure extra space and understand in-place tradeoffs.
06
Constraints
0/1 completeChoose algorithms that survive real input limits.
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