CPCS204 Data Structures 1 1432/1433H Lab

Lab Manual

CPCS204

1432/1433H

Lab - 3

Learning Procedure

1) Stage

J

^(Journey inside-out the concept) 2) Stage

a

1 (apply the learned)

3) Stage

v

^(verify the accuracy) 4) Stage

a

2 (assess ^{your work})

Laboratory 3:

Statement Purpose:

This lab will give you the description and implementation some basic Searching and Sorting Algorithms.

Activity Outcomes:

This lab teaches you the following topics:

 Learn some well-known sorting algorithms with their implementations.

 Use of Java.util.Arrays class and its under-class methods sort and binarySearch.

 Programming practice on sort methods for sorting array elements.

Instructor Note:

As pre-lab activity, review Ch2 & Ch14, from the book Data Structures with Java by John R. Hubbard and also the relevant instructor’s slides.

Names I.D.

1. .………..………. ………

2. ..……….. ………

3. .………... ………

4. .……….. ..……….

1) tage J ^(Journey)

Searching Algorithms:

A. Linear Search

linear search does O(n) comparisons on average.

B. Binary Search

Binary search does O(log n) comparisons at most which is much better than linear search.

Sorting Algorithms:

A. Selection Sort

Methodology (Ascending):

Algorithm (implemented in JAVA):

public static void selectionSort (int[] list) { int index, smallestIndex, minIndex, temp;

for (index = 0; index < list.length - 1; index++) {

smallestIndex = index;

for (minIndex= index+ 1; minIndex< list.length;

minIndex++)

if (list[minIndex] < list[smallestIndex]) smallestIndex = minIndex;

temp = list[smallestIndex];

list[smallestIndex] = list[index];

list[index] = temp;

} }

B. Bubble Sort

Methodology:

Algorithm (implemented as JAVA code):

public static void bubbleSort(int[] list) { int temp, counter, index;

for (counter = 0; counter < list.length; counter++) { for (index=0; index<list.length - 1 - counter;

index++) {

if(list[index] > list[index+1]) { temp = list[index];

list[index] = list[index+1];

list[index+1] = temp;

} } }

} //end bubbleSort

2) Stage a

1

(apply)

Example 1:

Built-in JAVA binarySearch()

 A static method of the class Arrays for searching the array element in the given arrays.

 Uses the binary search algorithm.

 Returns the index of the found element, but if element is not found then returns (-1)

 Applicable to arrays of any data type object.

 Array used in binarySearch() must be sorted.

 The binarsearch() method with Unsorted arrays may give wrong result.

 Array having duplicate elements when searched by binarySearch() method may return any of the duplicate element.

 Syntax: public static int binarySearch(Object[] array, Object key)

Task 1:

Write a statement to import the library of Arrays to the below program

Task 2:

Write and use a linearSearch() method to find index p of key in ar1

Task 3:

Write a statement using binarySearch() to find index p of key in ar1

Task 4:

Write a statement using to sort ar1 then use again binarySearch() to find index p of key in ar1

//Answer task 1 here

public class binary_search {

    public static void main(String[] args) {        int ar1[]={2,44,5,66,78,90,23,66};

       int p, key=78;

//Answer task 2 here //Answer task 3 here

       System.out.println("element found at index "+p);

//Answer task 4 here

       System.out.println("element found at index "+p);

    } }

Example 2:

Built-in JAVA sort()

 The sort operation uses a slightly optimized Dual-Pivot Quick sort algorithm that is stable and faster than traditional One-Pivot counterpart.

 Runs in O(n log n)time.

 Applicable to List objects consisting numbers or alphabetical content.

 Syntax: public static void sort(Object[] a)or

public static void sort(Object[] a, int fromIndex, int toIndex)

Task 1:

Use the built-in JAVA sorting method for an array's elements. Besides, printing array elements at once without loop (i.e. for or while… etc.) (Retype and try this code)

Task 2:

Clone (copy) array old to new array Arr then use sort(Object[] a, int fromIndex, int toIndex) to sort the right-half of array Arr. Print Arr after sort.

Potential Output:

old = [41,38,48,12,28,46,33,19,10,58] // the random generated array

num = [10,12,19,28,33,38,41,46,48,58] // sorted array

Arr = [41,38,48,12,28,10,19,33,46,58] // sorted right-half of array

3) Stage v ^(verify)

Programming Exercises Ex-1:

1. Write a program that reads 10 integer numbers and sort them with 2 different sorting algorithms.

2. Create 2 public classes. One called TestSorting and the other called Sorting.

3. Sorting class includes above 2 sorting methods (i.e. Selection, and Bubble) and 1 more method for printing the sorted array.

4. TestSorting class includes the main method, and uses java.util.scanner to enter 10 integers.

5. Creat and object of class Sorting Sort=new Sorting().

6. Then it calls the 2 methods in class Sorting then print the original array and the 2 sorted arrays. So, the output would be such that:

Please enter a num[0]: 5 Please enter a num[1]: 6 Please enter a num[2]: 9 Please enter a num[3]: 7 Please enter a num[4]: 2 Please enter a num[5]: 4 Please enter a num[6]: 3 Please enter a num[7]: 8 Please enter a num[8]: 10 Please enter a num[9]: 13 The ORIGINAL array is:

5 6 9 7 2 4 3 8 10 13

Sorted array by SELECTION sort is:

2 3 4 5 6 7 8 9 10 13

Sorted array by BUBBLE sort is:

2 3 4 5 6 7 8 9 10 13

Ex-2 (home activity):

(Sales Commissions) Use a one- dimensional array to solve the following problem: A company pays its salespeople on a commission basis. The salespeople receive $200 per week plus 9% of their gross sales for that week. For example, a

counters) that determines how many of the salespeople earned salaries in each of the following ranges (assume that each salesperson's salary is truncated to an integer amount):

$200-299

$300-399

$400-499

$500-599

$600-699

$700-799

$800-899

$900-999

$1000 and over

Summarize the results in tabular format.

4) Stage a

2

(assess) Lab Work:

In each laboratory you are assessed on your work within lab session based on your participation, discussions and achievement of lab activities. Thus, each lab has a portion of the (LAB WORK MARK).

Therefore, a checklist of each lab is used to evaluate your work. This checklist accounts the following criteria:

 Following the lab manual step by step

 Answering given questions concisely and precisely

 Practicing and implementing given examples correctly

 Writing code of required programming tasks

 Being focused, positive, interactive and serious during lab session

 Asking good questions or answering instructor questions if any

Note: performing given home activities or extra programming is highly recommended to improve your understanding, capability and programming skills.