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Build problem-solving instincts,
one rep at a time.

Work through data structures and algorithms in Python, JavaScript, Java, or C — judged against real test cases — and cement the concepts with written explanations.

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Foundations

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Warm-up problems to get comfortable with the workflow.

Complexity Analysis

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Big-O notation and reasoning about time and space.

Arrays & Hashing

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The bread and butter: arrays, hash maps, and sets.

Two Pointers

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Walking pointers from both ends or in tandem.

Stack & Queue

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LIFO and FIFO structures and where they shine.

Binary Search

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Halving the search space on sorted or monotonic data.

Sliding Window

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Maintaining a moving range over arrays and strings.

Linked Lists

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Nodes, pointers, and trade-offs versus arrays.

Trees & Graphs

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Hierarchies, grids, and graph traversal.

Recursion & DP

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Self-similar problems, memoization, and dynamic programming.

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FizzBuzz

foundations

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