These are problems, not algorithms. Each one is a named puzzle that keeps reappearing — sometimes verbatim, more often disguised — and each has a standard solution worth knowing cold.
Why they get their own section
An algorithm is a method; a classical problem is a question whose answer happens to be famous. Egg dropping is not an algorithm, it is a DP question. Keeping them apart makes the named algorithm catalog a clean toolbox and this page a clean pattern library.
Optimisation puzzles
- Egg Dropping
- Tower of Hanoi
- Josephus Problem
- N-Queens
- Knight’s Tour
- Water Jug / Die Hard
- Poisoned Wine
Sequence and array classics
- Maximum Subarray
- Stock Buy and Sell
- Trapping Rain Water
- Largest Rectangle in a Histogram
- Majority Element
- Dutch National Flag
- Celebrity Problem
- Next Greater Element
Counting and DP classics
- Coin Change
- Subset Sum and Partition
- Rod Cutting
- Word Break
- The Catalan Family — balanced brackets, triangulations, BSTs
- The Knapsack Problem
- Staircase / Tiling Counts
- Derangements
Matching and assignment
Graph classics
- Seven Bridges of Königsberg
- Travelling Salesman
- 8-Puzzle / 15-Puzzle
- Wolf, Goat and Cabbage
- Bridge Crossing (Torch)