Extend the 14-day foundations with graph modeling, union find, topological ordering, bridges, tree states, heaps, constrained DP, and backtracking. Some exercises are premium; revision guides are public.
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Clone structure, spread from multiple sources, then count route changes. Explain what a vertex and a transition mean in each problem.
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Keep the standalone DSU template. Join by shared evidence, not equal names, and count only successful merges. Exercises on this day are premium.
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Use indegrees for dependency ordering and low-link values for bridges. These are distinct invariants. Foreign Dictionary is a premium exercise.
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Compare a downward height, a path gain, a take/skip pair, and a coverage state. Camera placement is a greedy state algorithm, not the same numeric recurrence as house selection.
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Choose the comparator and bound frontier size. Compare sorting with k-way merging schedules. A heap orders candidates; the graph score still needs a proof. This day includes premium exercises.
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Reduce a circle to two linear ranges, then distinguish choosing an item once from unbounded reuse. The knapsack exercise is premium.
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Revisit a next-greater stack, reduce a binary matrix to histograms, then maintain a window's character deficits. Do not use one template for all three invariants.
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Explain which state is local to one candidate and must be restored. Contrast path-local visitation with a graph traversal's global visited set.