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Data Structure: Introduction

Data Structure: Introduction. Instructor: Dr. Engr. Sami ur Rahman. PhD: University of Technology Darmstadt, Germany MS: Freiburg University Germany M.Sc : University of Peshawar Professional Experience May 2013 - till date: Assistant Professor , UoM . 

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Data Structure: Introduction

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  1. Data Structure:Introduction

  2. Instructor: Dr. Engr. Sami ur Rahman • PhD: University of Technology Darmstadt, Germany • MS: Freiburg University Germany • M.Sc: University of Peshawar Professional Experience • May 2013 - till date: Assistant Professor ,UoM.  • Apr 2009 - Sep 2012: Research Associate, University of Technology Darmstadt, Germany.  Feb 2003– Sep 2006: Lecturer, University of Malakand.  • Jan 2003 - Mar 2003: Lecturer, UET Peshawar. • Sep 2002 - Jan 2003: Lecturer, Qurtuba University.  • Aug 2001 - Oct 2001: Lecturer ,CECOS University.  University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 2

  3. Motivation Chairs placement in the class (Demo) Array, stack example University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 3

  4. Data Structures • This course covers well-known data structures such as dynamic arrays, linked lists, stacks, queues, tree and graphs. • Implement data structures in C++ University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 4

  5. Need for Data Structures • Data structures organize data  more efficient programs. • More powerful computers  more complex applications. • More complex applications demand more calculations. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 5

  6. Organizing Data • Any organization for a collection of records that can be searched, processed in any order, or modified. • The choice of data structure and algorithm can make the difference between a program running in a few seconds or many days. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 6

  7. Efficiency • A solution is said to be efficient if it solves the problem within its resource constraints. • Space • Time • The cost of a solution is the amount of resources that the solution consumes. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 7

  8. Selecting a Data Structure Select a data structure as follows: • Analyze the problem to determine the resource constraints a solution must meet. • Determine the basic operations that must be supported. Quantify the resource constraints for each operation. • Select the data structure that best meets these requirements. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 8

  9. Data Structure Philosophy • Each data structure has costs and benefits. • Rarely is one data structure better than another in all situations. • A data structure requires: • space for each data item it stores, • time to perform each basic operation, • programming effort. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 9

  10. Goals of this Course • Reinforce the concept that costs and benefits exist for every data structure. • Learn the commonly used data structures. • These form a programmer's basic data structure “toolkit.” • Understand how to measure the cost of a data structure or program. • These techniques also allow you to judge the merits of new data structures that you or others might invent. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 10

  11. Arrays • Elementary data structure that exists as built-in in most programming languages. main( intargc, char** argv ) { int x[6]; int j; for(j=0; j < 6; j++) x[j] = 2*j; } University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 11

  12. Arrays • Array declaration: int x[6]; • An array is collection of cells of the same type. • The collection has the name ‘x’. • The cells are numbered with consecutive integers. • To access a cell, use the array name and an index: x[0], x[1], x[2], x[3], x[4], x[5] University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 12

  13. Array Layout x[0] Array cells are contiguous in computer memory The memory can be thought of as an array x[1] x[2] x[3] x[4] x[5] University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 13

  14. What is Array Name? • int x[6]; • ‘x’ is an array name. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 14

  15. Array Name • ‘x’ is not an lvalueint x[6];int n; x[0] = 5; x[1] = 2;x = 3; // not allowed x = a + b; // not allowed x = &n; // not allowed University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 15

  16. Dynamic Arrays • You would like to use an array data structure but you do not know the size of the array at compile time. • You find out when the program executes that you need an integer array of size n=20. • Allocate an array using the new operator:int* y = new int[20]; // or int* y = new int[n]y[0] = 10;y[1] = 15; // use is the same University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 16

  17. Dynamic Arrays • You would like to use an array data structure but you do not know the size of the array at compile time. • You find out when the program executes that you need an integer array of size n=20. • Allocate an array using the new operator:int* y = new int[20]; // or int* y = new int[n]y[0] = 10;y[1] = 15; // use is the same University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 17

  18. Dynamic Arrays • You would like to use an array data structure but you do not know the size of the array at compile time. • You find out when the program executes that you need an integer array of size n=20. • Allocate an array using the new operator:int* y = new int[20]; // or int* y = new int[n]y[0] = 10;y[1] = 15; // use is the same University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 18

  19. Dynamic Arrays • ‘y’ is a lvalue; it is a pointer that holds the address of 20 consecutive cells in memory. • It can be assigned a value. The new operator returns as address that is stored in y. • We can write: y = &x[0]; y = x; // x can appear on the right // y gets the address of the // first cell of the x array University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 19

  20. Dynamic Arrays • ‘y’ is a lvalue; it is a pointer that holds the address of 20 consecutive cells in memory. • It can be assigned a value. The new operator returns as address that is stored in y. • We can write: y = &x[0]; y = x; // x can appear on the right // y gets the address of the // first cell of the x array University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 20

  21. Dynamic Arrays • ‘y’ is a lvalue; it is a pointer that holds the address of 20 consecutive cells in memory. • It can be assigned a value. The new operator returns as address that is stored in y. • We can write: y = &x[0]; y = x; // x can appear on the right // y gets the address of the // first cell of the x array University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 21

  22. Dynamic Arrays • We must free the memory we got using the new operator once we are done with the y array. delete[ ] y; • We would not do this to the x array because we did not use new to create it. University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 22

  23. Questions University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 23

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