Data Structures Study Guide
Arrays, linked lists, trees, graphs, hash tables, heaps — and choosing the right structure for the problem.
Core topics in Data Structures
- Arrays and Linked Lists
- Stacks and Queues
- Trees
- Heaps
- Hash Tables
- Graphs
- Advanced Trees
- Tries
Why students struggle
Most students learn data structures as recipes. Interviewers ask 'which structure fits this problem?' and recipe-learners blank.
How Fennie helps
Fennie drills structure-selection separately from implementation: given a problem, predict the right structure before you code.
How to study Data Structures
- 01Implement each structure from scratch once
- 02Practice 'choose the structure' problems weekly
- 03Use Fennie for time/space complexity analysis
- 04Solve LeetCode by category, not random
Frequently asked questions
Should I memorize all data structures?
Memorize the trade-offs (insertion, lookup, deletion costs). Implementation details vary by language.
Is this useful for interviews?
Critical — most coding interviews test exactly this material.
Does Fennie generate coding problems?
Yes — Fennie generates LeetCode-style problems with explanations and complexity analysis.
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