CS1010J- Programming Methodology: Practical Assessment for Semester 1 Solved

INSTRUCTIONS TO CANDIDATES 

This assessment paper consists of 2 exercises on 7 pages.
This is an OPEN BOOK  You may refer to print copy or digital version of your module materials (e.g. lecture notes, tutorial paper) stored on your iPad, laptop, etc.
Calculators are allowed.
In line with the university rules, any form of communication with other students, or the use of unauthorised materials is considered cheating and you are liable to the disciplinary action.
The first 10 minutes of the assessment is reserved for you to read questions and design algorithms. You are not allowed to type your programs in this period of time.
Your invigilator will send you the question paper and skeleton programs. You are to use DrJava to write your programs. No other IDEs are allowed.
You may assume that all input data are valid; hence no input validation is needed.
You are responsible for submitting your programs to CodeCrunch by the end of the assessment.
You are NOT allowed to use any Java language syntax/knowledge not covered in weeks 1-9. If in doubt, please raise it in the practice assessment forum.
 

ALL THE BEST!                                                                 

Example Rough Marking Scheme for an Exercise of

Style:Write program description and student number in the program header.
Write a short and meaningful description for every method (except main).
Apply consistent indentation and good naming of variables.
Correctness and design:Graders will manually go through your program and award marks method by method.
Additional penalties:Program is not compilable: deduct 5 marks.
Break coding restrictions: deduct 5 - 20 marks, depending on severity.
Exercise 1: An Array of Integers
Given an array of distinct positive integers and another positive integer 𝑡𝑡, perform the following three tasks.

Report the largest difference between adjacent integers in the array.
For example, if the array is {13, 3, 4, 21}, the largest difference between neighbours is 17 (= 21 - 4). Note that the difference should be reported as a positive integer.

Report the number of tough numbers in the array.tough number is an integer 𝑛𝑛𝑛𝑛𝑛𝑛 of the form 𝑛𝑛𝑛𝑛𝑛𝑛 = 𝑘𝑘∗2𝑛𝑛+1, where 𝑘𝑘 and 𝑛𝑛 are positive integers, 𝑘𝑘 is odd, and 𝑘𝑘 <2𝑛𝑛.
A few examples are shown below.

3 is a tough number because 3 = 1*21 + 1 and 1 < 21.
4 is NOT a tough number.
13 is a tough number because 13 = 3*22 + 1 and 3 < 22.
21 is NOT a tough number. It can be expressed as 21 = 5*22 + 1 but 5 > 22.
Consequently, the array {13, 3, 4, 21} contains 2 tough numbers.

Report the number of smiling numbers in the array.smiling number is a positive integer that has the sum of its digits equals to a given positive integer 𝑡𝑡.
For example, if the array is {13, 3, 4, 21} and 𝑡𝑡 = 4, there are 2 smiling numbers in the array: 13 and 4; the sum of digits of each of them is 4.

In the given skeleton program ArrayOfInts.java, complete the following 4 methods.

int maxDiff(int[] arr) that returns the largest difference between adjacent integers in arr.
boolean isToughNum(int num) that checks if num is a tough number. It returns true if so, or false otherwise.
int countToughNum(int[] arr) that returns the number of tough numbers in arr.
int countSmilingNum(int[] arr, int t) that returns the number of smiling numbers in the array, i.e. the number of array elements that have the sum of their digits equals to t.
You may assume that arr contains at least 2 elements. Moreover, it doesn’t contain duplicate elements.

Take note of the following additional instructions/restrictions:

You are not allowed to change the main() method or method headers of other given methods.
Your methods may invoke each other and you may create additional arrays or write additional methods as necessary.
Two sample runs of the program are shown below with the user's input shown in bold.

Sample run #1

Enter the size of array: 4 

Enter the array: 13 3 4 21 

Maximum difference = 17

Number of tough numbers = 2

Enter t: 4 

Number of smiling numbers = 2

Sample run #2

Enter the size of array: 5 

Enter the array: 11 14 23 9 5 

Maximum difference = 14

Number of tough numbers = 2

Enter t: 5 

Number of smiling numbers = 3

Exercise 2: Employees
 

A company stores employee information in a table. One example is shown in Table 1 below. Each row of the table shows the information of one employee and it contains three fields: staff ID, age and salary. You may assume that all three fields are positive integers, staff ID is unique to each employee, and age is between 18 and 67, both ends inclusive.

ID
Age
Salary
111
35
4500
112
27
6600
113
25
2000
114
60
10000
115
60
6000
117
35
5000
118
60
30000
119
27
6600
122
40
4000
123
35
3400
 

Table 1. Records of 10 employees

Task 1
Suppose the above table is implemented as a two-dimensional (2D) array in your program. The company would like you to sort the 2D array by age in non-decreasing order, and for those employees with the same age, further sort by salary in non-decreasing order. If two employees have the same age and salary, their relative order in the original table should be preserved. Table 2 below shows the result of sorting Table 1 according to the stated criteria.

ID
Age
Salary
113
25
2000
112
27
6600
119
27
6600
123
35
3400
111
35
4500
117
35
5000
122
40
4000
115
60
6000
114
60
10000
118
60
30000
 

Table 2. Records of 10 employees after sorting

Write a method void swap(int[][] employees, int row1, int row2) that swaps two rows, row1 and row2, of the employees 
Write a method void sort(int[][] employees) that sorts the employees array according to the criteria stated on the previous page. You may choose selection sort, bubble sort or enhanced bubble sort covered in CS1010J. However, you are not allowed to call Java sorting APIs (e.g. you cannot use
Arrays.sort()).

Task 2
The company is interested to know which age most employees are of (i.e. most common age).

3) Write a method int[][] mostCommonAge(int[][] sortedEmployees) that checks which age is most common among employees. Note that there may be more than one most common age (see example below). The method then stores respective employees in a new 2D array and returns this new array. Respective employees should be stored in the new 2D array in the same order they appear in the parameter sortedEmployees array. You may assume that the company has at least one employee. Note that sortedEmployees array is already sorted in Task

1.

For the example shown in Table 2 on the previous page, there are two most common ages: 35 and 60. Hence the mostCommonAge() method will return a new array containing the following six employees.

ID
Age
Salary
123
35
3400
111
35
4500
117
35
5000
115
60
6000
114
60
10000
118
60
30000
 

Table 3. Two ages with the most number of employees

Complete the skeleton program Employees.java for the above two tasks. Take note of the following additional instructions/restrictions:

main(), readInput() and printArray() methods are complete and given. You are not allowed to change them.
You are not allowed to change the method headers of other given methods.
Your methods may invoke each other and you may create additional arrays or write additional methods as necessary.
Two sample runs of the program are given below with the user's input shown in bold. For your convenience of testing, test inputs are also appended to the back of the skeleton program.

 

Sample run #1

Enter the number of rows: 4 Enter data:

114  60 10000 

115  60 6000 

117  35 5000 

118  60 30000 

Sorted by age, then by salary:

117 35 5000

115 60 6000

114 60 10000

118 60 30000

Employees with the most common age:

115 60 6000

114 60 10000

118 60 30000
 

(Sample run #2 on the next page)

Sample run #2

Enter the number of rows: 10 Enter data:

35 4500 
27 6600 
25 2000 
60 10000 
60 6000 
35 5000 
60 30000 
27 6600 
40 4000 
35 3400 
Sorted by age, then by salary:

113 25 2000

112 27 6600

119 27 6600

123 35 3400

111 35 4500

117 35 5000

122 40 4000

115 60 6000

114 60 10000

118 60 30000

Employees with the most common age:

123 35 3400

111 35 4500

117 35 5000

115 60 6000

114 60 10000

118 60 30000