CS 312: Algorithm Analysis

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CS 312 Algorithm Analysis

• Lecture 15 Worked Example of Algorithm for
  Finding Strongly Connected Components

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Announcements

• HW 11 due now
• Questions?
• Project 2
• Help session tomorrow (Tuesday 2/13)
• Questions?
• Career Fair events
• see schedule!

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Clarifications Finding SCCs

• 1. Run depth-first search on GR
• 2. Run the connected components algorithm on G
• during this depth-first search, process the
  vertices in decreasing order of their post
  numbers from step 1
• i.e., dont worry about lexicographic order

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3 Questions

• Is it correct?
• Note how backward paths are found in step 1
• Note how forward paths are found in step 2
• How long does it take?
• 2 DFS passes
• O(V E) again!
• Can we do better?

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Next time

• Shortest Paths
• Breadth First Search
• Dijkstras Algorithm