| # | Problem | Difficulty | Topics |
|---|---|---|---|
| 241 | Counting Tilings | Hard | Advanced DPDPBitmask |
| 242 | Weighted Activity Selection | Hard | Advanced DPDPSorting |
| 243 | Longest Bitonic Subsequence | Hard | Advanced DPDPArray |
| 244 | Pattern Matching Automaton | Hard | Advanced DPDPAutomata |
| 245 | Profile DP Grid Paths | Hard | Advanced DPDPBitmask |
| 246 | Thread-Safe Queue | Hard | ConcurrencyQueueMutex |
| 247 | Read-Write Lock | Hard | ConcurrencyLockThreading |
| 248 | Custom Garbage Collector | Hard | System DesignMemoryReference Counting |
| 249 | Garbage Collector Simulator | Hard | System DesignMemoryGraph |
| 250 | Simple Database Engine | Hard | System DesignB-TreeFile I/O |
| 251 | HTTP Request Parser | Hard | System DesignStringParsing |
| 252 | JSON Parser from Scratch | Hard | System DesignStringRecursion |
| 253 | Compression Algorithm | Hard | System DesignHuffmanTree |
| 254 | Simple Virtual Machine | Hard | System DesignStackInstructions |
| 255 | Event Loop Simulator | Hard | System DesignQueueCallbacks |
| 256 | Convex Hull Algorithm | Hard | GeometryAlgorithmPoints |
| 257 | Line Segment Intersection | Hard | GeometryAlgorithmMath |
| 258 | Closest Pair of Points | Hard | GeometryDivide & ConquerPoints |
| 259 | Polygon Area Calculator | Hard | GeometryAlgorithmMath |
| 260 | Stable Matching (Gale-Shapley) | Hard | Advanced AlgorithmsAlgorithmMatching |