Lesson25 / 31

Module 1 · Recursion Fundamentals2 locked4 lessons

01What recursion is, with your first function traced
02The leap of faith (the skill that makes recursion click)
03Core recursion patterns in C# and how to hand-trace them (included with Full Access)
04Common recursion mistakes (and their C# symptoms) (included with Full Access)

Module 2 · From Recursion to Memoization4 locked4 lessons

05When to use recursion and when to prefer a loop (included with Full Access)
06Why naive recursion is slow: the Fib(6) recursion tree (included with Full Access)
07Top-down memoization and bottom-up tabulation (included with Full Access)
08Space optimization, and top-down vs bottom-up (included with Full Access)

Module 3 · Recognizing and Solving DP Problems4 locked4 lessons

09How to recognize a DP problem in the wild (included with Full Access)
10Climbing Stairs: the 'hello world' of DP (included with Full Access)
11House Robber: introducing a real decision (included with Full Access)
12Coin Change: the first minimum DP, and a famous greedy trap (included with Full Access)

Module 4 · 2D DP, Knapsack and Backtracking4 locked4 lessons

13Unique Paths and Longest Common Subsequence: 2D state (included with Full Access)
140/1 Knapsack: the capstone pattern (included with Full Access)
15What backtracking is, and how it differs from DP (included with Full Access)
16The universal backtracking template (included with Full Access)

Module 5 · Subsets, Permutations and N-Queens4 locked4 lessons

17Subsets: the cleanest first example (included with Full Access)
18Permutations and Combination Sum: undo and pruning (included with Full Access)
19N-Queens: the famous one, briefly (included with Full Access)
20Why these topics, specifically (included with Full Access)

Module 6 · Interview Relevance and Practice Plan4 locked4 lessons

21Will a C# developer be asked this in interviews? (included with Full Access)
22The one-page mental model (included with Full Access)
23Recurrence quick reference and the interview script (included with Full Access)
24A 4-week basics-first practice plan (45–60 min/day) (included with Full Access)

Module 7 · Module Practice Tests and Final Mock7 locked7 lessons

25Practice Test: Recursion Fundamentals (included with Full Access)
26Practice Test: From Recursion to Memoization (included with Full Access)
27Practice Test: Recognizing and Solving DP Problems (included with Full Access)
28Practice Test: 2D DP, Knapsack and Backtracking (included with Full Access)
29Practice Test: Subsets, Permutations and N-Queens (included with Full Access)
30Practice Test: Interview Relevance and Practice Plan (included with Full Access)
31Final Mock Interview: 25 Questions on Recursion, DP and Backtracking in C# (included with Full Access)

Module 7 · Module Practice Tests and Final Mock · Lesson 25 of 31

Practice Test: Recursion Fundamentals

12 min readTechInterviewNotes Editorial TeamUpdated 28 Oct 2026Save

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TechInterviewNotes Editorial Team · Updated 28 Oct 2026 ·