ITEC 2620M Introduction to Data Structures

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ITEC 2620MIntroduction to Data Structures

• Instructor Prof. Z. Yang
• Course Website http//people.math.yorku.ca/zyang
  /itec2620m.htm
• Office TEL 3049

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Complexity Estimation recurrence relations
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Key Points of this Lecture

• Estimation of recursive algorithms
• How many times?
• What does it cost?
• Basic Data Types I
• Stacks

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Relating Complexity Estimation to Recurrence
Relations

• How many times? is the number of recurrences
  levels of recursion
• What does it cost? is for an entire level of
  recursion
• linear recursion
• What does this recursive call cost?
• binary recursion
• What do all recursive calls at this level cost?

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Examples

• Factorial
• Binary search
• Mergesort
• Quicksort

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Abstract Data Types

• A way to specify the functionality of an entity
  without worrying about its implementation
• List ADT
•   interface SortedList
• public void insert (Object item)
• public object remove ()
• public boolean isInList ()

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Stacks

• A stack is a Last-In, First-Out LIFO buffer
• Only the top element of a stack is accessible
• When elements are added, they are pushed onto the
  top
• When elements are removed, they are popped off
  the top
• push() and pop() are the two defining functions
  of a stack
• Example
• Array-based Stacks