UNIVERSITY OF THE FREE STATE DEPARTMENT OF COMPUTER SCIENCE AND INFORMATICS RIS 214 MODULE TEST 1

Transcription

1 UNIVERSITY OF THE FREE STATE DEPARTMENT OF COMPUTER SCIENCE AND INFORMATICS RIS 214 MODULE TEST 1 DATE: 12 March 2014 TIME: 4 hours MARKS: 220 ASSESSORS: Prof. P.J. Blignaut & Mr G.J. Dollman BONUS MARKS: 7 MODERATOR: Dr T. Beelders This is an open-book test. You may use any of the listed text books for this module but you may not search for solutions online. Internet access will not be available for the duration of the assessment. You may use the tools available in VS2012 such as IntelliSense. No mobile computing devices may be active for the duration of the assessment (Mobile phones, tablets, etc). A maximum mark of 220 can be awarded for this assessment. Question 1 (Arrays, Algorithm complexity) Consider an array of integer numbers. Start with a new console application and save it as Question_1. Type the following Main() method. static void Main(string[] args) int[] Numbers = 4, 7, 2, 8, 4, 9, 2, 4, 7, 5 ; int mode = 0, F = 0; ModeForUnsortedArray(... Console.WriteLine("Mode = " + mode + "\nfrequency = " + F); Array.Sort(Numbers); mode = 0; F = 0; ModeForSortedArray(... Console.WriteLine("Mode = " + mode + "\nfrequency = " + F); Console.ReadKey(); //Main (6) 1.1 Write the method ModeForUnsortedArray. The method should take the Numbers array as first parameter. The method should also have two reference parameters to return the mode (element that occurs at the highest frequency) and frequency of the mode in the array. (12) 1.2 What is the complexity of the algorithm in 1.1? (2) 1.3 Write the method ModeForSortedArray. The method signature should be the same as for 1.1. The method should make use of the sorted nature of the array and implement a more efficient algorithm. (10) 1.4 What is the complexity of the algorithm in 1.3? (2) [32] 1

2 Question 2 (Recursion) Start with a new console application and save it as Question_2. Develop a recursive method to raise a number to a given integer power according to the definition: [13] 1 n = 0, x n = (x 2 ) n/2 n > 0, n is even x(x 2 ) n/2 n > 0, n is odd for example x 7 = x.(x 2 ) 3 = x.(x 2 ).(x 2 ) 2 x 8 = (x 2 ) 4 = ((x 2 ) 2 ) 2 x 9 = x.(x 2 ) 4 = x.((x 2 ) 2 ) 2 x 10 = (x 2 ) 5 = (x 2 ).((x 2 ) 2 ) 2 x 11 = x.(x 2 ) 5 = x.(x 2 ).((x 2 ) 2 ) 2 Use the following Main() method to test your method. You can change the hard coded values of x and n to test your method for various test data sets. static void Main(string[] args) int x = 2, n = 9; Console.WriteLine(x.ToString() + "^" + n.tostring() + " = " +... Console.Write("Press any key to exit..."); Console.ReadKey(); //Main Question 3 (Operator overloading, Indexers) A matrix can be defined as a two-dimensional array with m rows and n columns. The following two matrices have 2 rows and 3 columns each: [ ] [ ] Start with a new console application and save it as Question_3. 2

3 Consider the following Main() method with its output: static void Main(string[] args) //Define matrices 1 int[,] a = new int[,] 2, 1, 3, 1, 2, 1 ; 2 Matrix A = new Matrix(a); 3 Matrix B = new Matrix( new int[,] 1, 2, 1, 3, 2, 1 ); //Write A to the screen 4 Console.WriteLine("A"); 5 Console.Write(A.ToString()); 6 Console.WriteLine("A[1,2] = " + A[1, 2]); 7 Console.WriteLine(); //Write B to the screen 8 Console.WriteLine("B"); 9 Console.Write(B); 10 Console.WriteLine("B[1,0] = " + B[1, 0]); 11 Console.WriteLine(); //Write A + B to the screen 12 Console.WriteLine("A + B"); 13 Console.WriteLine(A + B); //Opportunity to read output 14 Console.ReadKey(); //Main Develop the class Matrix. 3.1 Provide a private data member, M, to be a two dimensional array of integers and will contain the data of the matrix. (2) 3.2 Develop the constructor of the class. The constructor should receive a two dimensional array as parameter and assign it to the data member of 3.1. (3) 3.3 Provide two properties, nrows and ncols respectively, to return the number of rows and the number of columns in the matrix. Note that the test data above is only test data and your class must make provision for any number of rows or columns. (4) 3.4 Override the ToString() method to return a string version of the content of the matrix. Comment out lines 6, 10 and 13 in the Main() method to test your program so far. (11) 3.5 Provide an indexer that will allow the class user to refer to an element in the matrix without reference to the inaccessible private two-dimensional array. In other words, a class user should be able to type A[1,2] to refer to the element in the second row and third column. Lines 6 and 10 should now also run. (8) 3.6 Two matrices of the same dimensions can be added together by adding the elements in corresponding positions. Define the + operator for the Matrix class. Line 13 should run now. (15) [ ] [ ] [ ] [43] 3

4 Question 4 (OOP) Start with a new Windows Forms application and save it as Question_4. Add the following interface to your application: interface IContainer<T> bool AddElement(T element); bool RemoveElement(T element); void Clear(); //interface 4.1 Develop a class, CContainer, that inherits from IContainer. The class will serve as generic base class for anything that contains some elements. The class must have a generic type parameter for the type of elements that it will contain. (3) Declare a protected generic list, Contents, that will contain elements of type T. (2) Provide an int property, Capacity, for the capacity (maximum number of elements) of the container. It must not be possible to change the property from outside the class. (3) The constructor of the class must instantiate the list of contents. The constructor should have a single parameter which must be used to assign a value for the capacity. (3) Provide an indexer which will return and set the value of the element in the i th position of the generic list. (7) Provide all necessary declarations for the following events: OnFull, OnEmpty, OnAdd and OnRemove. The OnAdd and OnRemove events must have an int parameter for the number of elements that are currently in the container. (8) Implement the interface method AddElement(T element). The method should add the given element to the list of elements and trigger the OnAdd event if the capacity will not be exceeded. Trigger the event OnFull if the addition means that the capacity has been reached with the addition. Return true if the element could be added and false otherwise. (9) Implement the interface method RemoveElement(T element). The method should remove the given element from the list and trigger the OnRemove event if it exists. Trigger the OnEmpty method if the removal means that the list will be empty after the removal. Return true of the element was removed successfully and false otherwise. (9) Develop a method Save() that will serialize the contents of the generic list. (9) Develop a method, Read(), that will deserialize the saved data of and enter the data in the generic list, Contents. Raise the OnAdd event. (10) Now consider the scenario of a parking lot. When a car enters the parking lot, a machine will provide a ticket with a unique number and the date-time stamp of entry. When the car leaves, a fee will be charged that is based on the time inside the parking lot. 4.2 Develop a struct, Car. (1) Provide a string property for the ticket number and a DateTime property for the time of entry. The properties must not be accessible from outside the struct. (4) The constructor must have a single string parameter for the ticket number that will be used to assign a value to the applicable property. The current date and time must be assigned to the property for the time of entry. (4) Mark the class as serializable. (1) 4

5 4.3 Develop a class, CParkingLot, that will inherit from CContainer. Specify the struct Car to be the type of elements that will be saved in the container class. (3) Provide a private decimal field for the tariff per hour. (1) The constructor must have a parameter for the capacity of the parking lot as well as for the tariff per hour. The constructor must use the parameter to assign the tariff per hour and pass the capacity through to the constructor of the base class. (4) Provide a public method that will return the fee due when a car leaves the parking lot. The car must be specified as a parameter. This fee must be calculated as the number of hours since entry, multiplied by the tariff per hour. (5) Provide an indexer that will return the car with a specified ticket number. Return default(car) if the ticket number is not found. (10) 4.4 Consider the screen print below Provide buttons to simulate the gate equipment to print a ticket upon entry and charge a fee upon exit of a car. Provide a vertical track bar to visualise the current status of the parking lot. (3) Declare an object of the class CParkingLot on class level. Instantiate a parking lot with a capacity of 8 cars and a tariff of R5 per hour in the form s constructor. Assign event handlers for all events. Set the Maximum property of the track bar to the capacity of the parking lot. (8) The OnAdd and OnRemove event handlers must update the Value property of the track bar. The OnFull and OnEmpty event handler must display appropriate message box. (12) The Check in button must ask the user for a ticket number and then call the AddElement method to add a new car to the parking lot. (5) The Check out button must ask the user for a ticket number and then call the Fee method and display the amount due. It must also call the RemoveElement method for the specific car. (11) Call the Save() method in the FormClosing() event handler. Call the method Read() in the Load() event handler. (4) [139] 5

6 MEMORANDUM Question 1 class Program static void Main(string[] args) int[] Numbers = 4, 7, 2, 8, 4, 9, 2, 4, 7, 5 ; int mode = 0, F = 0; 1. ModeForUnsortedArray(Numbers, ref mode, ref F ); Console.WriteLine("Mode = " + mode + "\nfrequency = " + F); Array.Sort(Numbers); mode = 0; F = 0; 1. ModeForSortedArray(Numbers, ref mode, ref F ); Console.WriteLine("Mode = " + mode + "\nfrequency = " + F); Console.ReadKey(); //Main 1.1 private static void ModeForUnsortedArray(int[] A, ref int mode, ref int F ) 1.2 O(n 2 ) for (int i = 0; i < A.Length; i++) int n = 1; for (int j = 1; j < A.Length; j++) if (A[i] == A[j]) n++; if (n > F) F = n; mode = A[i]; //for i //ModeForUnsortedArray 1.3 private static void ModeForSortedArray(int[] A, ref int mode, ref int F) int n = 1; for (int i = 1; i < A.Length; i++) if (A[i] == A[i - 1]) n++; else n = 1; if (n > F) F = n; mode = A[i]; //for i //ModeForUnsortedArray //class Program 1.4 O(n) 6

7 Question 2 class Program static void Main(string[] args) int x = 2, n = 9; Console.WriteLine(x.ToString() + "^" + n.tostring() + " = " + Power(x,n) ); Console.Write("Press any key to exit..."); Console.ReadKey(); //Main public static int Power(int x, int n ) //It does not really matter what the types are if (n == 0) return 1; if (n % 2 == 0) return Power(x*x, n/2 ); return x * Power(x*x, n/2 ); //class Program 7

8 Question 3 class Matrix 3.1. private int[,] M; //Constructor 3.2. public Matrix(int[,] M) this.m = M; 3.3. //Properties private int nrows get return M.GetLength(0); private int ncols get return M.GetLength(1); 3.4. //Override ToString(); public override string ToString() string s = ""; for (int i = 0; i < nrows; i++) for (int j = 0; j < ncols; j++) s += M[i, j] + "\t"; s += "\n"; return s; //ToString() 3.5. //Indexer public int this [int i, int j ] get return M[i, j]; set M[i, j] = value; 3.6. //Operator + public static Matrix operator + (Matrix A, Matrix B ) Matrix S = new Matrix(new int[a.nrows, A.nCols]); for (int i = 0; i < A.nRows; i++) for (int j = 0; j < A.nCols; j++) S[i, j] = A[i, j] + B[i, j]; return S; //operator + //class Matrix 8

9 Question delegate void delonfull(); delegate void delonempty(); delegate void delonadd(int Quantity); delegate void delonremove(int Quantity); 4.1 class CContainer<T> : IContainer <T> protected List<T> Contents; public int Capacity get; private set; public event delonfull OnFull; public event delonempty OnEmpty; public event delonadd OnAdd; public event delonremove OnRemove; //Constructor public CContainer(int Capacity ) Contents = new List<T>(); this.capacity = Capacity; //Constructor public T this [int i ] get return Contents[i]; set Contents[i] = value; //indexer private int Quantity get return Contents.Count; //Quantity public bool AddElement(T Content ) if (Contents.Count < Capacity) Contents.Add(Content); OnAdd(Quantity); if (Quantity >= Capacity) OnFull(); return true; return false; //AddContent public bool RemoveElement(T Content ) if (Contents.IndexOf(Content) >= 0) Contents.Remove(Content); OnRemove(Quantity); if (Quantity == 0) OnEmpty(); return true; return false; //RemoveContent 9

10 4.1.8 public void Save() FileStream fs = new FileStream("ParkingLot.bin", FileMode.Create); IFormatter formatter = new BinaryFormatter(); formatter.serialize(fs, Contents); fs.close(); //Save public void Read() FileStream fs = new FileStream("ParkingLot.bin", FileMode.Open); IFormatter formatter = new BinaryFormatter(); Contents = (List<T>)formatter.Deserialize(fs); fs.close(); OnAdd(Quantity); //Read //class CContainer [Serializable] struct Car public string TicketNumber get; private set; public DateTime dtin get; private set; public Car(string TicketNumber ) : this() this.ticketnumber = TicketNumber; this.dtin = DateTime.Now; //struct Car 4.3 class CParkingLot : CContainer <Car> private decimal TariffPerHour; public CParkingLot(int Capacity, decimal TariffPerHour ) : base(capacity) this.tariffperhour = TariffPerHour; public decimal Fee(Car car ) return ((int)datetime.now.subtract(car.dtin).totalhours + 1) * TariffPerHour; public Car this [string TicketNumber ] get int i = Contents.FindIndex(element => element.ticketnumber == TicketNumber); return i >= 0? Contents[i] : default(car) ; //indexer //CParkingLot 10

11 Form public partial class CfrmParkingLot : Form CParkingLot ParkingLot; public CfrmParkingLot() InitializeComponent(); ParkingLot = new CParkingLot(8, 5); ParkingLot.OnFull += ParkingLot_OnFull; ParkingLot.OnEmpty += ParkingLot_OnEmpty; ParkingLot.OnAdd += ParkingLot_OnAdd; ParkingLot.OnRemove += ParkingLot_OnRemove; trbarstatus.maximum = ParkingLot.Capacity; //Constructor private void CfrmParkingLot_Load(object sender, EventArgs e) ParkingLot.Read(); //CfrmParkingLot_Load private void CfrmParkingLot_FormClosing(object sender, FormClosingEventArgs e) ParkingLot.Save(); //CfrmParkingLot_FormClosing #region Event handlers private void ParkingLot_OnRemove(int Quantity) trbarstatus.value = Quantity; private void ParkingLot_OnAdd(int Quantity) trbarstatus.value = Quantity; private void ParkingLot_OnEmpty() MessageBox.Show("Empty", "PARKING LOT"); //ParkingLot_OnEmpty private void ParkingLot_OnFull() MessageBox.Show("Full", "PARKING LOT"); //ParkingLot_OnFull #endregion Event handlers 11

12 #region Buttons private void btncheckin_click(object sender, EventArgs e) string sticketnumber = Interaction.InputBox("Ticket number:", "PARKING LOT"); ParkingLot.AddElement(new Car(sTicketNumber) ); //btncheckin_click private void btncheckout_click(object sender, EventArgs e) string sticketnumber = Interaction.InputBox("Ticket number:", "PARKING LOT"); decimal Fee = ParkingLot.Fee(ParkingLot[sTicketNumber] ); if (ParkingLot.RemoveElement(ParkingLot[sTicketNumber])) MessageBox.Show("Fee: " + Fee.ToString("C"), "PARKING LOT"); else MessageBox.Show("No such car", "PARKING LOT"); //btncheckout_click #endregion Buttons //class CfrmParkingLot 12