Observed arrival · 2026-11-05
How slow can Algorithm 7.5.1H be?
An interactive technical exploration of how many rounds Knuth’s implementation of the Hopcroft–Karp matching algorithm can take.
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- Readers studying matching algorithms and algorithm analysis
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- The page says input behavior depends on the numbering of the girls and the order of each girl's list of boys.
Field notes
The walkthrough distinguishes the algorithm’s breadth-first construction of a directed acyclic graph of shortest augmenting paths from its depth-first search through that graph. It also names three counters—W5, W13, and W11—for different kinds of work, and notes that the ordering of vertices and adjacency lists affects the run. The page links to a report PDF and source code on GitHub.
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