The nine-stop interview path, from fundamentals to system design. Pick a node to learn it, drill a real problem, break a buggy snippet, or rehearse the interview.
18/82 demo problems3/9 patterns (demo)
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Sliding Window
Grow right, shrink left
Expand the right edge every step; shrink the left only while the window is invalid.
Store last-seen index to jump the left edge.
Track 'have vs need' counts for cover problems.
Suggested preparation (optional): . You can start here anytime.
