notebook/notes/algorithms/dfs.md

4.3 KiB

title TARGET DECK FILE TAGS tags
Depth-First Search Obsidian::STEM algorithm data_structure::graph
dfs
graph

Overview

Depth-first search operates on a graph G = \langle V, E \rangle and a source vertex s.

!dfs.gif

%%ANKI Basic What is DFS an acronym for? Back: Depth-first search. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Cloze Depth-first search is characterized by a graph and a {source vertex}. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Which of undirected and directed graphs is DFS applicable to? Back: Both. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic With respect to depth-first trees, what does the predecessor of a node N refer to? Back: The node from which N was discovered. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic What ADT is typically used to manage the set of most recently discovered DFS vertices? Back: A stack. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Cloze A {1:queue} is to {2:BFS} whereas a {2:stack} is to {1:DFS}. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Which vertices are not discovered during a graph DFS? Back: Those not reachable from the source vertex. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic What basic graph algorithm is the following a demonstration of? !dfs.gif Back: Depth-first search. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Which standard graph representation has worst-case DFS running time of O(\lvert V \rvert + \lvert E \rvert)? Back: The adjacency-list representation. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Given graph \langle V, E \rangle with adjacency-list representation, what is the worst-case run time of DFS? Back: O(\lvert V \rvert + \lvert E \rvert) Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Which standard graph representation has worst-case DFS running time of O(\lvert V \rvert^2)? Back: The adjacency-matrix representation. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Given graph \langle V, E \rangle with adjacency-matrix representation, what is the worst-case run time of DFS? Back: O(\lvert V \rvert^2) Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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%%ANKI Basic Why is DFS of an adjacency-list representation O(\lvert V \rvert + \lvert E \rvert)? Back: For each vertex being analyzed, we examine all of its adjacent vertices. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

END%%

%%ANKI Basic Why is DFS of an adjacency-matrix representation O(\lvert V \rvert^2)? Back: For each vertex being analyzed, we must examine \lvert V \rvert entries for adjacent vertices. Reference: Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).

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Bibliography

  • Thomas H. Cormen et al., Introduction to Algorithms, Fourth edition (Cambridge, Massachusett: The MIT Press, 2022).