Lecture topic-BruteForce

Design and analysis of algorithms chapter 3 31

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Unformatted text preview: xi − yi ) 2 i =1 2 d= k ∑ ( xi − yi ) 2 i =1 • How many different pairs of points? Design and Analysis of Algorithms – Chapter 3 31 Principle of counting: Product Rule Rule a The Product Rule • Suppose that a procedure can be broken down into a sequence of Suppose two tasks. If there are n1 ways to do the first task and for each of two these ways of doing the first task, there are n 2 ways to do the second these task, then there are n1n2 ways to do the procedure. task, Design and Analysis of Algorithms – Chapter 3 32 Principle of counting: Product Rule Rule a The Product Rule • Suppose that a procedure can be broken down into a sequence of Suppose two tasks. If there are n1 ways to do the first task and for each of two these ways of doing the first task, there are n 2 ways to do the second these task, then there are n1n2 ways to do the procedure. task, a Calculation • Applying the product rule, there are n*(n-1) pairs among n points Applying • Considering (a, b) and (b, a) as the same, we divide the above Considering number by 2 and thus, there are n*(n-1)/2 different pairs of points number Design and Analysis of Algorithms – Chapter 3 33 Brute force closest-pair algorithm a Closest pair • Problem: find the closest pair among n points in k-dimensional space • Algorithm: Compute distance between each pair of points and Compute identify the pair resulting in the shortest distance identify • Basic operation: d= k ∑ ( xi − yi ) 2 i =1 2 d=...
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This note was uploaded on 10/31/2013 for the course RAIK 283 taught by Professor Yinglu during the Fall '12 term at UNL.

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