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Greedy Algorithm

Master greedy algorithm patterns for interval scheduling, sorting, state tracking, and optimization problems. Learn when greedy works vs when DP is required, with rigorous proofs.

The Greedy Algorithm pattern makes locally optimal choices at each step to find globally optimal solutions. Master the three core patterns: interval scheduling (sort by end time), greedy with sorting (two-pointer matching), and greedy state tracking (maximum reach, cumulative balance). Learn rigorous proof techniques (exchange argument, greedy choice property, induction), understand when greedy works vs when DP is required, and avoid the #1 greedy mistake.

Featured Guide

Complete Guide

The Complete Greedy Algorithm Guide: Master All Patterns, Proofs, and Recognition Techniques

The ultimate comprehensive guide to greedy algorithms. Learn all patterns (interval scheduling, sorting, state tracking), when to use greedy vs DP, complete templates in multiple languages, proof techniques, and a systematic approach to solve any greedy problem.

25 min read

Interactive Tool

Roadmap

Greedy Visualizer

Interactive visualizer for Interval Scheduling. Step through the sort-by-end-time logic to understand the greedy choice property.

Greedy Algorithm Learning Roadmap: From Beginner to Interview-Ready in 5 Weeks

A structured 5-week learning path to master all greedy patterns. Progress from interval scheduling to advanced techniques with curated problems, rigorous proofs, and clear milestones.

Tutorials

Why Greedy Fails on Coin Change (And When You Need Dynamic Programming Instead)

Understand the classic counterexample that breaks greedy algorithms. Learn why greedy fails on Coin Change with arbitrary denominations, see the proof, and master when to use DP instead.

Greedy AlgorithmDynamic ProgrammingCoin Change

10 min

Interval Scheduling: Why Sort by End Time Works (Proof and Intuition)

Understand the most important greedy insight for interval scheduling. Learn why sorting by end time is optimal, see the rigorous proof, and understand why sorting by start time fails.

Greedy AlgorithmInterval SchedulingSorting

9 min

Wrong Sorting Criterion: The #1 Greedy Mistake (And How to Fix It)

Learn how to choose the right sorting criterion for greedy problems. Understand common mistakes, see examples where wrong sorting fails, and master the decision framework.

Greedy AlgorithmSortingCommon Mistakes

7 min

Jump Game: Why Greedy Beats DP (Proof and Complexity Comparison)

Understand why greedy is optimal for Jump Game while DP is overkill. Learn the O(n) greedy solution, see the proof, and compare with the O(n²) DP approach.

Greedy AlgorithmDynamic ProgrammingJump Game

8 min

Gas Station: Why Starting from the Failing Point Works (Greedy Proof)

Understand the counterintuitive greedy insight for Gas Station. Learn why starting from the failing point is optimal, see the rigorous proof, and master this pattern.

Greedy AlgorithmGas StationProof Techniques

8 min

Greedy Choice Property Explained: How to Identify and Prove It

Master the greedy choice property—the foundation of all greedy algorithms. Learn the definition, step-by-step framework for proving it, and examples where it holds vs fails.

Greedy AlgorithmGreedy Choice PropertyProof Techniques

8 min

Exchange Argument: The Most Powerful Greedy Proof Technique (With Examples)

Master the exchange argument—the gold standard for proving greedy correctness. Learn the step-by-step template, see detailed examples, and understand when to use this technique.

Greedy AlgorithmExchange ArgumentProof Techniques

9 min

Candy Problem: Why Two-Pass Greedy Works (And Why One Pass Fails)

Master the two-pass greedy technique for the Candy problem. Learn why one pass fails, understand the bidirectional constraint pattern, and see the complete solution.

Greedy AlgorithmTwo-PassCandy Problem

8 min

Greedy with Priority Queue: Pattern, Template, and When to Use It

Learn when and how to combine greedy with priority queues. Master the pattern for dynamic optimal selection with complete templates and examples.

Greedy AlgorithmPriority QueueHeap

10 min

Assign Cookies: Greedy Sorting Strategy Explained (With Proof)

Master the greedy sorting strategy for Assign Cookies. Learn why sorting both arrays works, see the proof, and understand the pattern.

Greedy AlgorithmSortingTwo Pointers

10 min

Greedy Two-Pointer Pattern: When Greedy Meets Two Pointers (Template and Examples)

Learn the hybrid greedy + two-pointer pattern. Master the template for matching and pairing problems with complete examples.

Greedy AlgorithmTwo PointersSorting

10 min

5 Common Interval Scheduling Mistakes (And How to Avoid Them)

Learn the most common mistakes in interval scheduling problems and how to debug them. Master the pattern with a comprehensive debugging checklist.

Greedy AlgorithmInterval SchedulingCommon Mistakes

10 min

Interval Scheduling Greedy: Template, Proof, and All Variants

Master the interval scheduling pattern with production-ready templates in Python, JavaScript, and Java. Learn why sorting by end time works, complete proof, and solve Meeting Rooms, Non-overlapping Intervals, and all variants.

Greedy AlgorithmInterval SchedulingActivity Selection

16 min

Greedy with Sorting: When to Sort, What to Sort By, and Complete Templates

Master greedy problems that require sorting. Learn systematic decision frameworks for choosing sorting criteria, complete templates for two-pointer greedy, and solve Assign Cookies, Boats to Save People, and all variants.

Greedy AlgorithmSortingTwo Pointers

15 min

Greedy State Tracking: Jump Game, Gas Station, and Cumulative Greedy Patterns

Master greedy problems that track cumulative state (balance, reach, fuel). Learn single-pass templates, understand why tracking state greedily works, and solve Jump Game, Gas Station, and all reachability problems.

Greedy AlgorithmState TrackingReachability

14 min

Greedy vs Dynamic Programming: When to Use Each, How to Decide, and Common Traps

Master the critical distinction between greedy and DP. Learn systematic decision frameworks, understand when greedy fails, see counterexamples, and avoid the #1 algorithm interview mistake.

Greedy AlgorithmDynamic ProgrammingAlgorithm Comparison

18 min

How to Prove Greedy Algorithms Correct: Exchange Argument, Induction, and Greedy Choice Property

Master the formal proof techniques for greedy algorithms. Learn exchange argument, induction, greedy choice property, and optimal substructure with step-by-step examples and templates.

Greedy AlgorithmProof TechniquesExchange Argument

17 min

Advanced Greedy Techniques: Priority Queues, Two-Pass Greedy, and Lookahead Strategies

Master advanced greedy patterns for Hard-level problems. Learn two-pass greedy (Candy), greedy with priority queues, lookahead strategies, and monotonic stack combinations.

Greedy AlgorithmAdvanced TechniquesPriority Queue

15 min