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Unformatted text preview: ” + edgelist[i].w) count = count + 1 union(edgelist[i].v
,edgelist[i].w) } i = i + 1 }
} 43 Union/Find and Disjoint Sets Sets stored as a parent array findset(v): trace upward in parent array
union(i,j): make one tree a child of a node it the other Improvements! Union by rank Path compression 44 Union by rank 45 Path Compression 46 Complexity for Kruskal’s A basic analysis leads us to (n2) But with the optimizations presented here, it can be
reduced to (m lg m) 47 Interval Selection 48 ActivitySelection Problem Problem: You and your classmates go on Semester
at Sea Each starting and ending at different times Many exciting activities each morning Maximize your “education” by doing as many as possible.
(They’re all equally good!) Welcome to the activity selection problem 49 Also called interval scheduling The Activities!
Id Start End 1
2 9:00
9:15 10:45
10:15 3
4 9:30
9:45 12:30
10:30 5
6
7
8
9
10
11 9:45
10:15
10:15
10:30
11:00
11:00
12:00 11:15
11:00
11:30
11:45
12:00
12:15
12:45 50 Activity
Fractals, Recursion and Crayolas
Tropical Drink Engineering with...
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 Spring '10
 HORTON
 Algorithms

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