Algorithms and Data Structures (INF1) Lecture 14/15 Hua Lu


 Anastasia Reeves
 2 years ago
 Views:
Transcription
1 Algorithms and Data Structures (INF1) Lecture 14/15 Hua Lu Department of Computer Science Aalborg University Fall 2007
2 This Lecture Shortest paths Problem preliminary Shortest paths in DAG BellmanMoore algorithm Dijkstra s algorithm 2
3 Motivation Example What is the shortest path from Århus to Skagen? Århus > Aalborg > Frederikshavn > Skagen Total cost: 4 hours This example is not so hard to figure out Only 4 possibilities Consider cases with Large number of nodes Multiple edge or path choices between the same pair of cities 1.5 Hjørring Viborg Skagen Aalborg 2 1 Frederikshavn 1 1 Århus 3
4 Shortest Path Problem Given a digraph whose edges are attached with costs, two of its vertices are specified as a and b Find a shortest path from a to b (if there exists one) s.t. the total cost of that path is the minimal This cost is called distance, denoted as d(a, b) Assumptions Edges may have negative costs Cycles with negative cost are not allowed If such a cycle is found, report it and stop the shortest path finding 4
5 Triangle Inequality If v is reachable from u, and w is reachable from v, we have d(u, w) d(u, v) + d(v, w) Proof d(u, v) indicates the shortest path from u to v d(v, w) indicates the shortest path from v to w d(u, v) + d(v, w) indicates one path from u to w A shortest path from u to w must exist, with cost d(u, w) d(u, w) d(u, v) + d(v, w) holds as d(u, w) indicates the shortest path! If = holds, v is on the shortest path from u to w In particular, if there is an edge between v and w, then d(u, w) d(u, v) + c(v, w) 5
6 Shortest Path Spanning Tree Given a digraph G with edge costs, each vertex is reachable from some start vertex a. Then, either G contains a negative cycle, or else it contains a spanning tree T, rooted at a, such that for each vertex v in G, the total cost of the path through T from a to v is equal to d(a, v) T reserves shortest path information Skagen 1 Such a tree is called a shortest path spanning tree E.g., start from Århus Hjørring 1 Aalborg Frederikshavn 1 Vibor g 1 2 Århus 6
7 Single Source Shortest Paths A single start vertex has been specified We call it a single source shortest path problem Three main algorithms exist for such problems Nodes # n, edge # m Topological sorting Dijkstra algorithm BellmanMoore algorithm 7
8 A Simple Recurrence The input digraph can have negative costs, but no negative cycles Still positive cycles possibly! Recurrence like the one we used in critical path d(a, a) = 0 d(a, v) = min{d(a, u) + c(u,v)}, u Pred(v) Pred(v) denotes the set of direct predecessors of v i.e. <u, v> is an edge The recurrence cannot be used due to possible cycles! For d(a, v), v can be involved in a cycle, recursion on v can be forever If G is a DAG, then this recurrence works as the basis for the topological sorting based algorithm of O(n+m) 8
9 BellmanMoore Algorithm d k (a, v) = the cost of a shortest path from a to v among all paths of length at most k Number of edges involved k If no such a path from a to v of length at most k, d k (a, v)= New recurrence d 0 (a, a) = 0 d 0 (a, v) = d k (a, v) = min{d k1 (a, v), min u Pred(v) {d k1 (a, u) + c(u, v)}} BellmanMoore algorithm Repeatedly compute d k (a, v) for k = 0, 1, 2, For a digraph with n nodes, the largest k to consider is n1 9
10 Complexity of BellmanMoore Alg k=0 k=1 k=n1 a=v 1 0 v 2 v n We need to compute this table column by column Dynamic programming! Cost to compute one d k (a, v) is O( Pred(v) ) Cost to compute one column is O(n+m) We have O(n) columns Total cost is O(n (n+m)) in the worst case 10
11 Negative Cycle Detection How to decide whether a digraph has a negative cycle or not? Use BellmanMoore algorithm and calculate also the column k=n The graph has a negative cycle if and only if d n (a, v) < d n1 (a, v) for some vertex v 11
12 Dijkstra s Algorithm Preliminaries Assumption No edge has negative cost Priority queue Like a symbol table, a set of entries Each entry has form of <key, value> Special operations find_min:entry_type Returns the entry in the priority queue whose key is minimum delete_min:entry_type Deletes and returns the entry that would be returned by find_min We use a priority queue when we are more concerned about items with extreme keys than the total order among all keys In shortest path finding, we care about the shortest path so far, not the order of all possible paths w.r.t. their lengths 12
13 Dijkstra s Algorithm Each vertex has fields v.visited, v.parent, v.distance A priority queue q When one vertex v is inserted into q, we regard v.distance as the key and v itself as the value, i.e., <v.distance, v> dijkstra(g:digraph, a:vertex_type) 1. for each vertex v, set v.visited:=false, v.distance:= 2. a.distance:=0; a.visited:=true; a.parent:=nil; q.insert(a) 3. while NOT q.empty do v:=q.delete_min for each edge (v, w) do if NOT w.visited then w.visited:=true; w.parent:=v; w.distance:=v.distance+c(v, w); q.insert(w) else if v.distance+c(v, w) < w.distance then w.distance:=v.distance+c(v, w); w.parent:=v 13
14 Correctness of Dijkstra s Algorithm v a x L: vertices Q: vertices R: removed from Q Loop Invariant z L: z.distance=d(a, z) still in Q z L: each successor of z is either in L or in Q z Q: z.distance is the length of one shortest path from node a to node z via vertices in L Prove it by induction on k, loop iteration vertices not visited yet 14
15 Complexity of Dijkstra s Algorithm Cost of step 1 is O(n) Cost of step 2 is O(1) Cost of step 3 is O(n+m) + time cost on the priority queue delete_min: n times insert: n times distance update: m times Total cost O(n + m + n (T(delete_min)) + n (T(insert)) + m (T(dist_update))) Priority queue implementation Linked list Fibonacci heap delete_min O(n) O(log n) insert O(1) O(1) distance update O(1) O(1) Total time cost O(n 2 ) O(n log n + m) 15
16 Shortest Paths Summary Arbitrary digraphs Use BellmanMoore algorithm O(n (n+m)) O(n 3 ) if m=θ(n 2 ) Digraphs with nonnegative costs Use Dijkstra s algorithm O(n log n+m) O(n 2 ) if m=θ(n 2 ) DAGs Use topological sorting based algorithm O(n+m) Better than Dijkstra s algorithm, but still O(n 2 ) if m=θ(n 2 ) 16
17 Next Lecture Minimum spanning trees Definitions Kruskal s algorithm Prim s algorithm Course conclusion 17
CSE 326, Data Structures. Sample Final Exam. Problem Max Points Score 1 14 (2x7) 2 18 (3x6) 3 4 4 7 5 9 6 16 7 8 8 4 9 8 10 4 Total 92.
Name: Email ID: CSE 326, Data Structures Section: Sample Final Exam Instructions: The exam is closed book, closed notes. Unless otherwise stated, N denotes the number of elements in the data structure
More informationData Structures and Algorithms Written Examination
Data Structures and Algorithms Written Examination 22 February 2013 FIRST NAME STUDENT NUMBER LAST NAME SIGNATURE Instructions for students: Write First Name, Last Name, Student Number and Signature where
More informationBinary Heaps. CSE 373 Data Structures
Binary Heaps CSE Data Structures Readings Chapter Section. Binary Heaps BST implementation of a Priority Queue Worst case (degenerate tree) FindMin, DeleteMin and Insert (k) are all O(n) Best case (completely
More informationThe A* Search Algorithm. Siyang Chen
The A* Search Algorithm Siyang Chen Introduction A* (pronounced Astar ) is a search algorithm that finds the shortest path between some nodes S and T in a graph. Heuristic Functions Suppose we want to
More informationGraph. Consider a graph, G in Fig Then the vertex V and edge E can be represented as:
Graph A graph G consist of 1. Set of vertices V (called nodes), (V = {v1, v2, v3, v4...}) and 2. Set of edges E (i.e., E {e1, e2, e3...cm} A graph can be represents as G = (V, E), where V is a finite and
More informationExam study sheet for CS2711. List of topics
Exam study sheet for CS2711 Here is the list of topics you need to know for the final exam. For each data structure listed below, make sure you can do the following: 1. Give an example of this data structure
More informationThe UnionFind Problem Kruskal s algorithm for finding an MST presented us with a problem in datastructure design. As we looked at each edge,
The UnionFind Problem Kruskal s algorithm for finding an MST presented us with a problem in datastructure design. As we looked at each edge, cheapest first, we had to determine whether its two endpoints
More informationCMSC 451: Graph Properties, DFS, BFS, etc.
CMSC 451: Graph Properties, DFS, BFS, etc. Slides By: Carl Kingsford Department of Computer Science University of Maryland, College Park Based on Chapter 3 of Algorithm Design by Kleinberg & Tardos. Graphs
More informationTheorem A graph T is a tree if, and only if, every two distinct vertices of T are joined by a unique path.
Chapter 3 Trees Section 3. Fundamental Properties of Trees Suppose your city is planning to construct a rapid rail system. They want to construct the most economical system possible that will meet the
More informationCOT5405 Analysis of Algorithms Homework 3 Solutions
COT0 Analysis of Algorithms Homework 3 Solutions. Prove or give a counter example: (a) In the textbook, we have two routines for graph traversal  DFS(G) and BFS(G,s)  where G is a graph and s is any
More informationGraph Algorithms. Ananth Grama, Anshul Gupta, George Karypis, and Vipin Kumar
Graph Algorithms Ananth Grama, Anshul Gupta, George Karypis, and Vipin Kumar To accompany the text Introduction to Parallel Computing, Addison Wesley, 3. Topic Overview Definitions and Representation Minimum
More informationChapter 2 Paths and Searching
Chapter 2 Paths and Searching Section 2.1 Distance Almost every day you face a problem: You must leave your home and go to school. If you are like me, you are usually a little late, so you want to take
More informationWarshall s Algorithm: Transitive Closure
CS 0 Theory of Algorithms / CS 68 Algorithms in Bioinformaticsi Dynamic Programming Part II. Warshall s Algorithm: Transitive Closure Computes the transitive closure of a relation (Alternatively: all paths
More information1. What s wrong with the following proofs by induction?
ArsDigita University Month : Discrete Mathematics  Professor Shai Simonson Problem Set 4 Induction and Recurrence Equations Thanks to Jeffrey Radcliffe and Joe Rizzo for many of the solutions. Pasted
More informationCpt S 223. School of EECS, WSU
The Shortest Path Problem 1 ShortestPath Algorithms Find the shortest path from point A to point B Shortest in time, distance, cost, Numerous applications Map navigation Flight itineraries Circuit wiring
More informationCS711008Z Algorithm Design and Analysis
CS711008Z Algorithm Design and Analysis Lecture 7 Binary heap, binomial heap, and Fibonacci heap 1 Dongbo Bu Institute of Computing Technology Chinese Academy of Sciences, Beijing, China 1 The slides were
More informationMinimum cost maximum flow, Minimum cost circulation, Cost/Capacity scaling
6.854 Advanced Algorithms Lecture 16: 10/11/2006 Lecturer: David Karger Scribe: Kermin Fleming and Chris Crutchfield, based on notes by Wendy Chu and Tudor Leu Minimum cost maximum flow, Minimum cost circulation,
More informationTrees and Fundamental Circuits
Trees and Fundamental Circuits Tree A connected graph without any circuits. o must have at least one vertex. o definition implies that it must be a simple graph. o only finite trees are being considered
More informationMathematical Induction. Lecture 1011
Mathematical Induction Lecture 1011 Menu Mathematical Induction Strong Induction Recursive Definitions Structural Induction Climbing an Infinite Ladder Suppose we have an infinite ladder: 1. We can reach
More informationGRAPH THEORY and APPLICATIONS. Trees
GRAPH THEORY and APPLICATIONS Trees Properties Tree: a connected graph with no cycle (acyclic) Forest: a graph with no cycle Paths are trees. Star: A tree consisting of one vertex adjacent to all the others.
More informationLoop Invariants and Binary Search
Loop Invariants and Binary Search Chapter 4.3.3 and 9.3.11  Outline Ø Iterative Algorithms, Assertions and Proofs of Correctness Ø Binary Search: A Case Study  2  Outline Ø Iterative Algorithms, Assertions
More informationMinimum Spanning Trees
Minimum Spanning Trees Algorithms and 18.304 Presentation Outline 1 Graph Terminology Minimum Spanning Trees 2 3 Outline Graph Terminology Minimum Spanning Trees 1 Graph Terminology Minimum Spanning Trees
More informationMath 443/543 Graph Theory Notes 4: Connector Problems
Math 443/543 Graph Theory Notes 4: Connector Problems David Glickenstein September 19, 2012 1 Trees and the Minimal Connector Problem Here is the problem: Suppose we have a collection of cities which we
More informationCS268: Geometric Algorithms Handout #5 Design and Analysis Original Handout #15 Stanford University Tuesday, 25 February 1992
CS268: Geometric Algorithms Handout #5 Design and Analysis Original Handout #15 Stanford University Tuesday, 25 February 1992 Original Lecture #6: 28 January 1991 Topics: Triangulating Simple Polygons
More informationCMPS 102 Solutions to Homework 1
CMPS 0 Solutions to Homework Lindsay Brown, lbrown@soe.ucsc.edu September 9, 005 Problem.. p. 3 For inputs of size n insertion sort runs in 8n steps, while merge sort runs in 64n lg n steps. For which
More informationSample Problems in Discrete Mathematics
Sample Problems in Discrete Mathematics This handout lists some sample problems that you should be able to solve as a prerequisite to Computer Algorithms Try to solve all of them You should also read
More informationIE 680 Special Topics in Production Systems: Networks, Routing and Logistics*
IE 680 Special Topics in Production Systems: Networks, Routing and Logistics* Rakesh Nagi Department of Industrial Engineering University at Buffalo (SUNY) *Lecture notes from Network Flows by Ahuja, Magnanti
More information4 Basics of Trees. Petr Hliněný, FI MU Brno 1 FI: MA010: Trees and Forests
4 Basics of Trees Trees, actually acyclic connected simple graphs, are among the simplest graph classes. Despite their simplicity, they still have rich structure and many useful application, such as in
More informationData Structures in Java. Session 16 Instructor: Bert Huang
Data Structures in Java Session 16 Instructor: Bert Huang http://www.cs.columbia.edu/~bert/courses/3134 Announcements Homework 4 due next class Remaining grades: hw4, hw5, hw6 25% Final exam 30% Midterm
More informationExample 5.5. The heuristics are demonstrated with this example of n=5 vertices and distances in the following matrix:
39 5.3. HEURISTICS FOR THE TSP Notation: f = length of the tour given by the algortihm a f = length of the optimal tour min Most of the following heuristics are designed to solve symmetric instances of
More informationLong questions answer Advanced Mathematics for Computer Application If P= , find BT. 19. If B = 1 0, find 2B and 3B.
Unit1: Matrix Algebra Short questions answer 1. What is Matrix? 2. Define the following terms : a) Elements matrix b) Row matrix c) Column matrix d) Diagonal matrix e) Scalar matrix f) Unit matrix OR
More informationDynamic programming. Doctoral course Optimization on graphs  Lecture 4.1. Giovanni Righini. January 17 th, 2013
Dynamic programming Doctoral course Optimization on graphs  Lecture.1 Giovanni Righini January 1 th, 201 Implicit enumeration Combinatorial optimization problems are in general NPhard and we usually
More informationHome Page. Data Structures. Title Page. Page 1 of 24. Go Back. Full Screen. Close. Quit
Data Structures Page 1 of 24 A.1. Arrays (Vectors) nelement vector start address + ielementsize 0 +1 +2 +3 +4... +n1 start address continuous memory block static, if size is known at compile time dynamic,
More informationLecture Note 05 EECS 4101/5101 Instructor: Andy Mirzaian. SKEW HEAPS: SelfAdjusting Heaps
Lecture Note 05 EECS 40/50 Instructor: Andy Mirzaian SKEW HEAPS: SelfAdjusting Heaps In this handout we describe the skew heap data structure, a selfadjusting form of heap related to the leftist heap
More informationApproximation Algorithms
Approximation Algorithms or: How I Learned to Stop Worrying and Deal with NPCompleteness Ong Jit Sheng, Jonathan (A0073924B) March, 2012 Overview Key Results (I) General techniques: Greedy algorithms
More informationA tree can be defined in a variety of ways as is shown in the following theorem: 2. There exists a unique path between every two vertices of G.
7 Basic Properties 24 TREES 7 Basic Properties Definition 7.1: A connected graph G is called a tree if the removal of any of its edges makes G disconnected. A tree can be defined in a variety of ways as
More informationData Structures Fibonacci Heaps, Amortized Analysis
Chapter 4 Data Structures Fibonacci Heaps, Amortized Analysis Algorithm Theory WS 2012/13 Fabian Kuhn Fibonacci Heaps Lacy merge variant of binomial heaps: Do not merge trees as long as possible Structure:
More informationA. V. Gerbessiotis CS Spring 2014 PS 3 Mar 24, 2014 No points
A. V. Gerbessiotis CS 610102 Spring 2014 PS 3 Mar 24, 2014 No points Problem 1. Suppose that we insert n keys into a hash table of size m using open addressing and uniform hashing. Let p(n, m) be the
More information6 March 2007 1. Array Implementation of Binary Trees
Heaps CSE 0 Winter 00 March 00 1 Array Implementation of Binary Trees Each node v is stored at index i defined as follows: If v is the root, i = 1 The left child of v is in position i The right child of
More informationThe Goldberg Rao Algorithm for the Maximum Flow Problem
The Goldberg Rao Algorithm for the Maximum Flow Problem COS 528 class notes October 18, 2006 Scribe: Dávid Papp Main idea: use of the blocking flow paradigm to achieve essentially O(min{m 2/3, n 1/2 }
More informationNetwork File Storage with Graceful Performance Degradation
Network File Storage with Graceful Performance Degradation ANXIAO (ANDREW) JIANG California Institute of Technology and JEHOSHUA BRUCK California Institute of Technology A file storage scheme is proposed
More informationOutline BST Operations Worst case Average case Balancing AVL Redblack Btrees. Binary Search Trees. Lecturer: Georgy Gimel farb
Binary Search Trees Lecturer: Georgy Gimel farb COMPSCI 220 Algorithms and Data Structures 1 / 27 1 Properties of Binary Search Trees 2 Basic BST operations The worstcase time complexity of BST operations
More informationCOS 226 Algorithms and Data Structures Fall Final
COS 22 Algorithms and Data Structures Fall 200 Final This test has 4 questions worth a total of 00 points. You have 80 minutes. The exam is closed book, except that you are allowed to use a one page cheatsheet
More informationScheduling Shop Scheduling. Tim Nieberg
Scheduling Shop Scheduling Tim Nieberg Shop models: General Introduction Remark: Consider non preemptive problems with regular objectives Notation Shop Problems: m machines, n jobs 1,..., n operations
More informationGraphs. Graph G=(V,E): representation
Graphs G = (V,E) V the vertices of the graph {v 1, v 2,..., v n } E the edges; E a subset of V x V A cost function cij is the cost/ weight of the edge (v i, v j ) Graph G=(V,E): representation 1. Adjacency
More informationWhy? A central concept in Computer Science. Algorithms are ubiquitous.
Analysis of Algorithms: A Brief Introduction Why? A central concept in Computer Science. Algorithms are ubiquitous. Using the Internet (sending email, transferring files, use of search engines, online
More informationTriangle deletion. Ernie Croot. February 3, 2010
Triangle deletion Ernie Croot February 3, 2010 1 Introduction The purpose of this note is to give an intuitive outline of the triangle deletion theorem of Ruzsa and Szemerédi, which says that if G = (V,
More informationSocial Media Mining. Graph Essentials
Graph Essentials Graph Basics Measures Graph and Essentials Metrics 2 2 Nodes and Edges A network is a graph nodes, actors, or vertices (plural of vertex) Connections, edges or ties Edge Node Measures
More informationSolutions to Exercises 8
Discrete Mathematics Lent 2009 MA210 Solutions to Exercises 8 (1) Suppose that G is a graph in which every vertex has degree at least k, where k 1, and in which every cycle contains at least 4 vertices.
More informationCIS 700: algorithms for Big Data
CIS 700: algorithms for Big Data Lecture 6: Graph Sketching Slides at http://grigory.us/bigdataclass.html Grigory Yaroslavtsev http://grigory.us Sketching Graphs? We know how to sketch vectors: v Mv
More informationV. Adamchik 1. Graph Theory. Victor Adamchik. Fall of 2005
V. Adamchik 1 Graph Theory Victor Adamchik Fall of 2005 Plan 1. Basic Vocabulary 2. Regular graph 3. Connectivity 4. Representing Graphs Introduction A.Aho and J.Ulman acknowledge that Fundamentally, computer
More informationDiversity Coloring for Distributed Data Storage in Networks 1
Diversity Coloring for Distributed Data Storage in Networks 1 Anxiao (Andrew) Jiang and Jehoshua Bruck California Institute of Technology Pasadena, CA 9115, U.S.A. {jax, bruck}@paradise.caltech.edu Abstract
More informationSection IV.1: Recursive Algorithms and Recursion Trees
Section IV.1: Recursive Algorithms and Recursion Trees Definition IV.1.1: A recursive algorithm is an algorithm that solves a problem by (1) reducing it to an instance of the same problem with smaller
More informationBinary Heap Algorithms
CS Data Structures and Algorithms Lecture Slides Wednesday, April 5, 2009 Glenn G. Chappell Department of Computer Science University of Alaska Fairbanks CHAPPELLG@member.ams.org 2005 2009 Glenn G. Chappell
More informationAlgorithms and Data Structures
Algorithms and Data Structures CMPSC 465 LECTURES 2021 Priority Queues and Binary Heaps Adam Smith S. Raskhodnikova and A. Smith. Based on slides by C. Leiserson and E. Demaine. 1 Trees Rooted Tree: collection
More informationMemoization/Dynamic Programming. The String reconstruction problem. CS125 Lecture 5 Fall 2016
CS125 Lecture 5 Fall 2016 Memoization/Dynamic Programming Today s lecture discusses memoization, which is a method for speeding up algorithms based on recursion, by using additional memory to remember
More informationBicolored Shortest Paths in Graphs with Applications to Network Overlay Design
Bicolored Shortest Paths in Graphs with Applications to Network Overlay Design Hongsik Choi and HyeongAh Choi Department of Electrical Engineering and Computer Science George Washington University Washington,
More informationCSL851: Algorithmic Graph Theory Semester I Lecture 4: August 5
CSL851: Algorithmic Graph Theory Semester I 201314 Lecture 4: August 5 Lecturer: Naveen Garg Scribes: Utkarsh Ohm Note: LaTeX template courtesy of UC Berkeley EECS dept. Disclaimer: These notes have not
More informationCOURSE: B.TECHECE. IV Sem. Data structure Using C. b) Deletion of element in an array
COURSE: B.TECHECE. IV Sem Data structure Using C 1. Determine the formula to find the address location of an element in three dimensions array, suppose each element takes four bytes of space & elements
More information5. A full binary tree with n leaves contains [A] n nodes. [B] log n 2 nodes. [C] 2n 1 nodes. [D] n 2 nodes.
1. The advantage of.. is that they solve the problem if sequential storage representation. But disadvantage in that is they are sequential lists. [A] Lists [B] Linked Lists [A] Trees [A] Queues 2. The
More informationMatrix Product. MatrixMultiply (A, B) Cost of multiplying these matrices is p q r.
Dynamic Programming A powerful paradigm for algorithm design. Often leads to elegant and efficient algorithms when greedy or diideandconquer don t work. DP also breaks a problem into subproblems, but
More informationEuclidean Minimum Spanning Trees Based on Well Separated Pair Decompositions Chaojun Li. Advised by: Dave Mount. May 22, 2014
Euclidean Minimum Spanning Trees Based on Well Separated Pair Decompositions Chaojun Li Advised by: Dave Mount May 22, 2014 1 INTRODUCTION In this report we consider the implementation of an efficient
More informationBig O and Limits Abstract Data Types Data Structure Grand Tour. http://gcc.gnu.org/onlinedocs/libstdc++/images/pbds_different_underlying_dss_1.
Big O and Limits Abstract Data Types Data Structure Grand Tour http://gcc.gnu.org/onlinedocs/libstdc++/images/pbds_different_underlying_dss_1.png Consider the limit lim n f ( n) g ( n ) What does it
More informationCpt S 223. School of EECS, WSU
Priority Queues (Heaps) 1 Motivation Queues are a standard mechanism for ordering tasks on a firstcome, firstserved basis However, some tasks may be more important or timely than others (higher priority)
More informationSEMITOTAL AND TOTAL BLOCKCUTVERTEX GRAPH
CHAPTER 3 SEMITOTAL AND TOTAL BLOCKCUTVERTEX GRAPH ABSTRACT This chapter begins with the notion of block distances in graphs. Using block distance we defined the central tendencies of a block, like Bradius
More informationTrees. Tree Definitions: Let T = (V, E, r) be a tree. The size of a tree denotes the number of nodes of the tree.
Trees After lists (including stacks and queues) and hash tables, trees represent one of the most widely used data structures. On one hand trees can be used to represent objects that are recursive in nature
More informationDiscrete Mathematics (2009 Spring) Induction and Recursion (Chapter 4, 3 hours)
Discrete Mathematics (2009 Spring) Induction and Recursion (Chapter 4, 3 hours) ChihWei Yi Dept. of Computer Science National Chiao Tung University April 17, 2009 4.1 Mathematical Induction 4.1 Mathematical
More informationGRAPH THEORY LECTURE 4: TREES
GRAPH THEORY LECTURE 4: TREES Abstract. 3.1 presents some standard characterizations and properties of trees. 3.2 presents several different types of trees. 3.7 develops a counting method based on a bijection
More informationOPTIMAL DESIGN OF DISTRIBUTED SENSOR NETWORKS FOR FIELD RECONSTRUCTION
OPTIMAL DESIGN OF DISTRIBUTED SENSOR NETWORKS FOR FIELD RECONSTRUCTION Sérgio Pequito, Stephen Kruzick, Soummya Kar, José M. F. Moura, A. Pedro Aguiar Department of Electrical and Computer Engineering
More informationQuiz 2 Solutions. Solution: False. Need stable sort.
Introduction to Algorithms April 13, 2011 Massachusetts Institute of Technology 6.006 Spring 2011 Professors Erik Demaine, Piotr Indyk, and Manolis Kellis Quiz 2 Solutions Problem 1. True or false [24
More informationDynamic Programming. Applies when the following Principle of Optimality
Dynamic Programming Applies when the following Principle of Optimality holds: In an optimal sequence of decisions or choices, each subsequence must be optimal. Translation: There s a recursive solution.
More informationPlanar Tree Transformation: Results and Counterexample
Planar Tree Transformation: Results and Counterexample Selim G Akl, Kamrul Islam, and Henk Meijer School of Computing, Queen s University Kingston, Ontario, Canada K7L 3N6 Abstract We consider the problem
More informationStrategic Deployment in Graphs. 1 Introduction. v 1 = v s. v 2. v 4. e 1. e 5 25. e 3. e 2. e 4
Informatica 39 (25) 237 247 237 Strategic Deployment in Graphs Elmar Langetepe and Andreas Lenerz University of Bonn, Department of Computer Science I, Germany Bernd Brüggemann FKIE, FraunhoferInstitute,
More informationAny two nodes which are connected by an edge in a graph are called adjacent node.
. iscuss following. Graph graph G consist of a non empty set V called the set of nodes (points, vertices) of the graph, a set which is the set of edges and a mapping from the set of edges to a set of pairs
More information Easy to insert & delete in O(1) time  Don t need to estimate total memory needed.  Hard to search in less than O(n) time
Skip Lists CMSC 420 Linked Lists Benefits & Drawbacks Benefits:  Easy to insert & delete in O(1) time  Don t need to estimate total memory needed Drawbacks:  Hard to search in less than O(n) time (binary
More information2.3 Scheduling jobs on identical parallel machines
2.3 Scheduling jobs on identical parallel machines There are jobs to be processed, and there are identical machines (running in parallel) to which each job may be assigned Each job = 1,,, must be processed
More information6.263 Data Communication Networks
6.6 Data Communication Networks Lecture : Internet Routing (some slides are taken from I. Stoica and N. Mckewon & T. Griffin) Dina Katabi dk@mit.edu www.nms.csail.mit.edu/~dina Books Text Book Data Communication
More informationUnicyclic Graphs with Given Number of Cut Vertices and the Maximal Merrifield  Simmons Index
Filomat 28:3 (2014), 451 461 DOI 10.2298/FIL1403451H Published by Faculty of Sciences Mathematics, University of Niš, Serbia Available at: http://www.pmf.ni.ac.rs/filomat Unicyclic Graphs with Given Number
More informationRotation Operation for Binary Search Trees Idea:
Rotation Operation for Binary Search Trees Idea: Change a few pointers at a particular place in the tree so that one subtree becomes less deep in exchange for another one becoming deeper. A sequence of
More informationPseudocode Analysis. COMP3600/6466 Algorithms Lecture 5. Recursive Algorithms. Asymptotic Bounds for Recursions
COMP600/6466 Algorithms Lecture 5 Pseudocode Analysis Iterative Recursive S 0 Dr. Hassan Hijazi Prof. Weifa Liang Recursive Algorithms Asymptotic Bounds for Recursions Total running time = Sum of times
More informationAlgorithms Chapter 12 Binary Search Trees
Algorithms Chapter 1 Binary Search Trees Outline Assistant Professor: Ching Chi Lin 林 清 池 助 理 教 授 chingchi.lin@gmail.com Department of Computer Science and Engineering National Taiwan Ocean University
More informationAnalysis of Algorithms I: Binary Search Trees
Analysis of Algorithms I: Binary Search Trees Xi Chen Columbia University Hash table: A data structure that maintains a subset of keys from a universe set U = {0, 1,..., p 1} and supports all three dictionary
More informationLecture Notes on Spanning Trees
Lecture Notes on Spanning Trees 15122: Principles of Imperative Computation Frank Pfenning Lecture 26 April 26, 2011 1 Introduction In this lecture we introduce graphs. Graphs provide a uniform model
More informationProblem Set 7 Solutions
8 8 Introduction to Algorithms May 7, 2004 Massachusetts Institute of Technology 6.046J/18.410J Professors Erik Demaine and Shafi Goldwasser Handout 25 Problem Set 7 Solutions This problem set is due in
More informationHandout #Ch7 San Skulrattanakulchai Gustavus Adolphus College Dec 6, 2010. Chapter 7: Digraphs
MCS236: Graph Theory Handout #Ch7 San Skulrattanakulchai Gustavus Adolphus College Dec 6, 2010 Chapter 7: Digraphs Strong Digraphs Definitions. A digraph is an ordered pair (V, E), where V is the set
More informationDiscrete Mathematics, Chapter 5: Induction and Recursion
Discrete Mathematics, Chapter 5: Induction and Recursion Richard Mayr University of Edinburgh, UK Richard Mayr (University of Edinburgh, UK) Discrete Mathematics. Chapter 5 1 / 20 Outline 1 Wellfounded
More informationBinary Heaps * * * * * * * / / \ / \ / \ / \ / \ * * * * * * * * * * * / / \ / \ / / \ / \ * * * * * * * * * *
Binary Heaps A binary heap is another data structure. It implements a priority queue. Priority Queue has the following operations: isempty add (with priority) remove (highest priority) peek (at highest
More information2. (a) Explain the strassen s matrix multiplication. (b) Write deletion algorithm, of Binary search tree. [8+8]
Code No: R05220502 Set No. 1 1. (a) Describe the performance analysis in detail. (b) Show that f 1 (n)+f 2 (n) = 0(max(g 1 (n), g 2 (n)) where f 1 (n) = 0(g 1 (n)) and f 2 (n) = 0(g 2 (n)). [8+8] 2. (a)
More informationOutline. NPcompleteness. When is a problem easy? When is a problem hard? Today. Euler Circuits
Outline NPcompleteness Examples of Easy vs. Hard problems Euler circuit vs. Hamiltonian circuit Shortest Path vs. Longest Path 2pairs sum vs. general Subset Sum Reducing one problem to another Clique
More informationCS2 Algorithms and Data Structures Note 11. BreadthFirst Search and Shortest Paths
CS2 Algorithms and Data Structures Note 11 BreadthFirst Search and Shortest Paths In this last lecture of the CS2 Algorithms and Data Structures thread we will consider the problem of computing distances
More informationSolutions to Homework 6
Solutions to Homework 6 Debasish Das EECS Department, Northwestern University ddas@northwestern.edu 1 Problem 5.24 We want to find light spanning trees with certain special properties. Given is one example
More informationTwo General Methods to Reduce Delay and Change of Enumeration Algorithms
ISSN 13465597 NII Technical Report Two General Methods to Reduce Delay and Change of Enumeration Algorithms Takeaki Uno NII2003004E Apr.2003 Two General Methods to Reduce Delay and Change of Enumeration
More informationGraph Theory Problems and Solutions
raph Theory Problems and Solutions Tom Davis tomrdavis@earthlink.net http://www.geometer.org/mathcircles November, 005 Problems. Prove that the sum of the degrees of the vertices of any finite graph is
More informationInternational Journal of Software and Web Sciences (IJSWS) www.iasir.net
International Association of Scientific Innovation and Research (IASIR) (An Association Unifying the Sciences, Engineering, and Applied Research) ISSN (Print): 22790063 ISSN (Online): 22790071 International
More information6.042/18.062J Mathematics for Computer Science October 3, 2006 Tom Leighton and Ronitt Rubinfeld. Graph Theory III
6.04/8.06J Mathematics for Computer Science October 3, 006 Tom Leighton and Ronitt Rubinfeld Lecture Notes Graph Theory III Draft: please check back in a couple of days for a modified version of these
More informationNow is the time. For all good men PERMUTATION GENERATION. Princeton University. Robert Sedgewick METHODS
Now is the time For all good men PERMUTATION GENERATION METHODS To come to the aid Of their party Robert Sedgewick Princeton University Motivation PROBLEM Generate all N! permutations of N elements Q:
More information1. Sorting (assuming sorting into ascending order) a) BUBBLE SORT
DECISION 1 Revision Notes 1. Sorting (assuming sorting into ascending order) a) BUBBLE SORT Make sure you show comparisons clearly and label each pass First Pass 8 4 3 6 1 4 8 3 6 1 4 3 8 6 1 4 3 6 8 1
More information6.852: Distributed Algorithms Fall, 2009. Class 2
.8: Distributed Algorithms Fall, 009 Class Today s plan Leader election in a synchronous ring: Lower bound for comparisonbased algorithms. Basic computation in general synchronous networks: Leader election
More informationUnit 4: Layout Compaction
Unit 4: Layout Compaction Course contents Design rules Symbolic layout Constraintgraph compaction Readings: Chapter 6 Unit 4 1 Design rules: restrictions on the mask patterns to increase the probability
More informationHomework MA 725 Spring, 2012 C. Huneke SELECTED ANSWERS
Homework MA 725 Spring, 2012 C. Huneke SELECTED ANSWERS 1.1.25 Prove that the Petersen graph has no cycle of length 7. Solution: There are 10 vertices in the Petersen graph G. Assume there is a cycle C
More information