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Advanced coding challenges
Practise advanced with 15 coding challenges, from easy to hard. Every challenge runs in your browser with instant tests, an AI review of your code and community solutions to compare.
Medium · 3 Hard · 12
Skills you'll practise: 4-neighbor checksArea calculationBitmask DPCycle detectionDAG DPDivide and conquerEdge countingFrequency mapsGraph algorithmsGrid simulationGrow and shrink windowsInterval DP
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All challenges
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Hard
Shortest Delivery Tour
Visit every city once and return home as cheaply as possible.
You'll learn
Bitmask DPTraveling salesman
No solutions yet
Medium
Game of Life Step
Advance Conway's Game of Life by one generation.
You'll learn
Grid simulationNeighbor counting
No solutions yet
Hard
Strongly Connected Components
Count groups of nodes that can all reach each other.
You'll learn
Graph algorithmsTarjan or Kosaraju
No solutions yet
Hard
Minimum Window Substring
Find the shortest piece of text containing all required characters.
You'll learn
Grow and shrink windowsFrequency maps
No solutions yet
Hard
Longest Path in a DAG
Find the heaviest path in a task dependency graph.
You'll learn
Topological orderDAG DP
No solutions yet
Hard
Median of Two Sorted Arrays
Find the median of two sorted lists combined.
You'll learn
Partition searchO(log n)
No solutions yet
Hard
Largest Rectangle in a Histogram
Find the largest rectangle that fits under a histogram.
You'll learn
Monotonic stackArea calculation
No solutions yet
Medium
K-th Smallest Element
Find the k-th smallest value without fully sorting.
You'll learn
QuickselectPartitioning
No solutions yet
Hard
Word Break
Decide whether text can be split into dictionary words.
You'll learn
Prefix DPString segmentation
No solutions yet
Hard
Course Schedule Order
Order courses so every prerequisite comes first.
You'll learn
Kahn's algorithmCycle detection
No solutions yet
Hard
Count Inversions
Count the out-of-order pairs in a list.
You'll learn
Merge sortDivide and conquer
No solutions yet
Hard
Trapping Rain Water
Compute how much rain water an elevation map holds.
You'll learn
Two pointersPrefix maxima
No solutions yet
Medium
Island Perimeter
Measure the coastline of land cells in a grid.
You'll learn
Edge counting4-neighbor checks
No solutions yet
Hard
Sliding Window Maximum
Report the maximum of every window of k numbers.
You'll learn
Monotonic dequeO(n) windows
No solutions yet
Hard
Matrix Chain Multiplication
Find the cheapest order to multiply a chain of matrices.
You'll learn
Interval DPOptimization
No solutions yet
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