CSEC1 Algorithms and Data Structures 1

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CSEC1Algorithms and Data Structures 1

• lecturer Dr.Matthew Montebello
• office CB 409
• e-mail mmont_at_cs.um.edu.mt
• credit 1
• lectures 10
• assignment 1 (50)
• test 1 (50)
• webpage
• http//staff.um.edu.mt/mmon1/lectures/dip_cs_edu

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Lecture Schedule

• 1. Introduction to CSE-C1.
• 2. Abstract Data Types (ADTs)
• 3. Lists.
• 4. Stacks.
• 5. Queues.
• 6. Deques.
• 7. Trees.
• 8. Sets.
• 9. Past Papers other Queries.
• 10. Closure Pre-Test Revision.

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Introduction to CSE-C1

• What will happen during lectures.
• Practice makes perfect.
• Web pages of interest
• http//pascal.about.com/compute/
  pascal/library/weekly/aa011901.htm
• http//taoyue.com/tutorials/pascal
• http//www.cs.virginia.edu/mab8e/
  structures.html
• http//allserv.rug.ac.be/vfack/files/
  algori.html
• Use of Compiler.
• Other procedures.

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2. Abstract Data Types

• Todays lecture
• Overview of schedule
• Recall of last lecture
• General introd. to DS Algs.
• DS in everyday life
• Introduction to ADTs
• Overview of ADTs covered
• Normal processes of an ADT
• Closure Summary
• Next Lecture
• Questions.

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General Introd. to DS Algs

• A Data Structure is an Abstract Data Type that
  has three following components
• Operations Specifications of external appearance
  of a data structure
• Storage Structures Organizations of data
  implemented in lower level data structures
• Algorithms Description on how to manipulate
  information in the storage structures to obtain
  the results defined for the operations

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General Introd. to DS Algs

• An algorithm is a finite set of instructions
  chosen from a finite, fixed set of instructions.
• Every algorithm must satisfy the following
  criteria.
• Input It has zero or more input parameters.
• Output It produces at least one output
  parameter.
• Definiteness Each instruction must be clear and
  unambiguous.
• Finiteness For every input, it executes only a
  finite number of instructions.
• Effectiveness Every instruction must be
  sufficiently basic so that a machine can execute
  the instruction.

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DS in Everyday Life

• We use DS in the normal things we do during the
  day, like
• Shopping list
• List of Shores
• Telephone directory
• Same thing with algorithms, we implicitly define
  our own set of instructions on how we manipulate
  these daily DS, like
• Add/removing items
• Prioritizing items
• Data to enter with each item

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Introduction to ADTs

• Definition of Abstract Data Type
• Class of data objects (i.e., instances of the
  data type) with a set of the operations that can
  be applied to the objects (telling what to do
  instead of how to do)
• ADT is specified by
• a set of operations which can be applied to the
  objects and
• a set of properties (called axioms) which all the
  objects and operations must satisfy.

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Introduction to ADTs

• Advantage of Abstract Data Type
• Modularity (Encapsulation) The definition of
  operations isolates implementation of ADT from
  construction of a program using ADT.
• Cohesiveness (Self-maintaining) Implementation of
  ADT can be changed without modifying programs
  using ADT.
• Data Abstraction (minimal Coupling) The ADT does
  not depend on other processes during input or
  output.

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Introduction to ADTs

• Simple example of ADT
• Name of ADT Integer
• Operations that it will perform
• CreateDefines an identifier with an undefined
  value
• AssignAssigns the value of one integer
  identifier or value to another integer identifier
  
• IsEqualreturns true if the values (or values
  associated with identifiers) of the two integers
  are the same
• LessThanreturns true if the value of the first
  integer is less than the value of the second
  integer
• Negativereturns the negative of the integer
  value
• Sumreturns the sum of two integer values

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Overview of ADTs covered

• As already discussed and as seen in the schedule
  we will be covering in some detail the following
  DS based on the concept of ADT
• Lists.
• Stacks.
• Queues.
• Deques.
• Trees.
• Sets.
• Tables

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Normal Process of an ADT

• The standard operations that we will be doing
  with each of the DS we will be covering will be
  explained in theory and programmed in the Pascal
  language.
• Operations include
• Define
• Create
• Add to
• Remove from
• Search
• Empty

• Check if full
• Check if empty
• Destroy