Easy14 steps
Two Sum
Find the pair of indices whose values add up to a target.
Arrays & Hash Map
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10 modules ready
Starter algorithm library
Easy8 steps
Binary Search
Narrow a sorted range with low, mid, and high pointers.
Sorted Array
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Medium32 steps
Merge Sort
Split, sort, and merge values into ordered segments.
Arrays & Recursion
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Easy16 steps
Reverse Linked List
Mutate next pointers while preserving the remaining chain.
Linked Nodes
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Medium22 steps
Tree Level Order
Traverse tree levels through a FIFO queue.
Binary Tree
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Medium48 steps
Number of Islands
Mark connected land cells with recursive traversal.
Matrix / DFS
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Medium36 steps
BFS Shortest Path
Explore a graph in breadth-first order to reach a target.
Graph
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Hard64 steps
Dijkstra
Relax weighted edges with a priority queue.
Weighted Graph
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Easy18 steps
Valid Parentheses
Use a stack to validate matching bracket pairs.
Stack
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Medium20 steps
Container With Water
Move dual pointers to maximize contained water.
Arrays & Pointers
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