Cornell CS 4820: Introduction to Analysis of Algorithms
CS 4820 is Cornell's upper-level algorithms course — greedy algorithms, divide and conquer, dynamic programming, network flow, and NP-completeness and reductions — with a heavy emphasis on proving correctness and analyzing complexity. It's a required CS core course and a capstone of the theory sequence.
Fennie is independent and not affiliated with Cornell University. This is an unofficial study guide.
Build my CS 4820 study planWhat makes it hard
The course is proof-heavy: you don't just design algorithms, you prove they're correct and analyze their running time rigorously, and on exams you invent algorithms for unseen problems and justify them. Dynamic programming and reductions are the famous walls — recognizing the right subproblem structure or the right reduction is a creative skill that only volume builds.
What you'll cover
- • Greedy algorithms
- • Divide and conquer
- • Dynamic programming
- • Network flow
- • NP-completeness and reductions
- • Correctness proofs and complexity analysis
The CS 4820 study guide
How to study for Cornell CS 4820, step by step.
- 1
Practice inventing algorithms, not memorizing them
CS 4820 exams give you unseen problems and ask you to design and prove an algorithm. Solve many problems from scratch — recognizing a known solution is worthless when the problem is new.
- 2
Always prove correctness and runtime
Half the credit is the proof. For every algorithm you design, write the correctness argument and the complexity analysis, because the exam grades the justification as much as the idea.
- 3
Drill dynamic programming until the structure is reflex
DP is the classic wall: it's about seeing the subproblem and recurrence. Work many DP problems until identifying the state and transition feels routine rather than mysterious.
- 4
Build a reductions playbook
NP-completeness reductions reward pattern familiarity. Collect the standard reductions and the problems they come from, then practice mapping new problems onto known hard ones.
- 5
Write solutions under exam conditions
Before each prelim, solve unfamiliar problems on blank paper under time pressure. The course rewards producing complete, rigorous arguments fast — a different skill from following a posted solution.
- 6
Space the problem-solving with Fennie
Upload your CS 4820 syllabus and Fennie's Daily Plan spreads algorithm-design and proof practice across the weeks, gives dynamic programming and reductions extra reps, and syncs review to prelims — with quizzes generated from the actual course content. Free to start.
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How Fennie helps with CS 4820
Fennie's Daily Plans spread CS 4820's algorithm-design practice across the term, with dynamic programming and reductions given the extra reps they need and review synced to prelims. Chat works through why an algorithm is correct and how to structure a DP recurrence or a reduction, building the from-scratch problem-solving the exams demand.
FAQ
Is CS 4820 at Cornell hard?
Yes — it's one of the harder required CS courses because it's proof-heavy and exams ask you to invent and rigorously justify algorithms for unseen problems. Dynamic programming and NP-completeness reductions are the usual walls, and only solving many problems builds the needed intuition.
How do I study for CS 4820?
Solve unfamiliar problems from scratch and prove every algorithm's correctness and runtime, since that's exactly what exams test. Drill dynamic programming until spotting the subproblem is reflexive, and build a playbook of standard NP-completeness reductions.
What should I know before CS 4820?
Solid CS 2800 discrete-math and proof skills plus comfort with data structures from CS 2110. The course assumes you can write a clean induction or contradiction proof, since correctness arguments are half of nearly every problem.
Pass CS 4820 with a plan, not a cram
Upload your CS 4820 materials and Fennie generates a Daily Plan paced to your deadline — plus chat, flashcards, and quizzes built from the actual course content.
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