CoursesTrees & GraphsTopological Sort
All Ancestors of a Node in a DAG
Who are v's ancestors? Flip the question: search FORWARD from each source u and stamp u on everything it reaches. Iterate sources 0..n-1 and every list comes out sorted for free.
AlgoFox Pro
Trees & Graphs is part of AlgoFox Pro
You can read the whole course outline here. The exercises are in the app, along with your streak, your mistake review, and the progress that carries across your devices.
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