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DSA/Greedy Algorithms

Greedy Algorithms

This is a premium interview-preparation course built around the single hardest skill in greedy problems: **knowing when greedy is correct**. Anyone can sort an array and grab the best-looking option; the interview signal is being able to say *why* that choice can never block the optimum. You will start with the mental model — the greedy-choice property, optimal substructure, and the exchange argument — and then work through curated problems grouped by the patterns interviewers actually test: interval greedy, scheduling, array reachability, string construction, heap-assisted greedy, and advanced sorting-based greedy. Every problem teaches the insight first, proves the greedy choice, then shows a clean Java 17 implementation.

27

Curated lessons

7

Learning modules

8h 2m

Est. study time

10

Target companies

What you'll learn

  • Recognise the tell-tale signs of a greedy problem and distinguish them from problems that require dynamic programming.
  • Justify a greedy choice with an informal exchange argument — the proof interviewers listen for.
  • Apply the core greedy templates: sort-then-sweep intervals, earliest-deadline scheduling, farthest-reach arrays, and heap-assisted selection.
  • Communicate correctness the way senior and staff interviewers expect: greedy insight, why it works, complexity.

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Learning roadmap

Work top to bottom — each module builds on the last.

  1. 1

    Greedy Fundamentals

    Greedy-choice property + optimal substructure

    The mental model: what makes a greedy choice safe, and how to prove it with an exchange argument before writing any code.

    6/6 problems48m
  2. 2

    Interval Greedy

    Sort by endpoint, then sweep and compare boundaries

    Sort by start or end, then sweep — the interval family behind merging, overlap removal, and point covering.

    4/4 problems1h 13m
  3. 3

    Scheduling

    Sort by deadline/end, allocate with a heap or counter

    Order events by the right key — start, end, or deadline — to pack the most work into limited time or resources.

    4/4 problems1h 17m
  4. 4

    Array Greedy

    Maintain a running frontier / balance in one sweep

    Track a single running best — farthest reach, running balance, or local demand — in one linear pass.

    4/4 problems1h 27m
  5. 5

    String Greedy

    Last-occurrence boundaries + monotonic stack / frequency

    Use last-occurrence and frequency information to cut, prune, or arrange characters optimally.

    3/3 problems57m
  6. 6

    Heap + Greedy

    Greedy selection with a heap to swap out the worst pick

    Let a priority queue undo or upgrade earlier greedy choices, keeping the best feasible set at every step.

    3/3 problems1h 23m
  7. 7

    Advanced Greedy

    Clever sort order + insertion / two-pointer pairing

    Non-obvious sort keys and two-pointer pairings that turn a hard construction into a clean linear or log-linear pass.

    3/3 problems57m

Modules

7 themed modules from fundamentals to advanced.

1

Greedy Fundamentals

The mental model: what makes a greedy choice safe, and how to prove it with an exchange argument before writing any code.

6/6 problems48m
0%
2

Interval Greedy

Sort by start or end, then sweep — the interval family behind merging, overlap removal, and point covering.

4/4 problems1h 13m
0%
3

Scheduling

Order events by the right key — start, end, or deadline — to pack the most work into limited time or resources.

4/4 problems1h 17m
0%
4

Array Greedy

Track a single running best — farthest reach, running balance, or local demand — in one linear pass.

4/4 problems1h 27m
0%
5

String Greedy

Use last-occurrence and frequency information to cut, prune, or arrange characters optimally.

3/3 problems57m
0%
6

Heap + Greedy

Let a priority queue undo or upgrade earlier greedy choices, keeping the best feasible set at every step.

3/3 problems1h 23m
0%
7

Advanced Greedy

Non-obvious sort keys and two-pointer pairings that turn a hard construction into a clean linear or log-linear pass.

3/3 problems57m
0%

Full curriculum

21 problems and 6 concept lessons in learning order.

Techniques you'll master

Activity SelectionArrayBFS LayersCircular ArrayConstructionCorrectnessCountingDecision MakingDynamic ProgrammingExchange ArgumentFoundationsGreedyHash MapHashingHeapHeapsInsertionIntervalsInterview FrameworkLast OccurrenceLexicographic OrderLocal ConstraintsMathMonotonic StackOptimal SubstructureOrder ReconstructionPairingPatternsPrefix MaximumPrefix SumPriority QueueProofsReachabilityRecurrenceResource AllocationSchedulingSimulationSortingStringSweep LineTrade-offsTreeMapTwo PassesTwo Pointers