Question 1 [20 points]

Transcription

1 Question 1 [20 points] a) Write the following mathematical expression in Java. c=math.sqrt(math.pow(a,2)+math.pow(b,2)- 2*a*b*Math.cos(gamma)); b) Write the following Java expression in mathematical notation. p = Math.atan2(z, Math.sqrt(x * x + y * y)); P=arctangent2 (z, x 2 + y 2 ) c) True or false? A && B is the same as B && A for any Boolean condition A and B. False d) What does the following code print? for (int i = 0; i < 5; i++) for (int j = 0; j < 5; j++) System.out.print(i * j % 5); System.out.println(); Page 1/6

2 Question 2 [20 points] The Fibonacci sequence is defined by the following rule. The first two values in the sequence are 1 and 1. Every subsequent value is the sum of the two values preceding it. For example, the third value is = 2, the fourth value is = 3, and the fifth is = 5. If fn denotes the nth value in the Fibonacci sequence, then Write a program that prompts the user for n and prints the first n values in the Fibonacci sequence. Use a class FibonacciGenerator with a method nextnumber. Hint: There is no need to store all values for fn. You only need the last two values to compute the next one in the series: fold1 = 1; fold2 = 1; fnew = fold1 + fold2; After that, discard fold2, which is no longer needed, and set fold2 to fold1 and fold1to fnew. Your generator class will be tested with this runner program: public class FibonacciRunner public static void main(string[] args) Scanner in = new Scanner(System.in); System.out.println("Enter n:"); int n = in.nextint(); FibonacciGenerator fg = new FibonacciGenerator(); for (int i = 1; i <= n; i++) System.out.println(fg.nextNumber()); NOTE 1: Provide the answer in the next page. NOTE 2: Provide Documentation. Page 2/6

3 Question 2 continue /** Class used to generate a Fibonacci number with a given input */ public class FibonacciGenerator /** Construct a FibonacciGenerator object to generate a Fibonacci number */ See the Sample Solution of A10 Page 3/6

4 Question 3 [30 points] Following is the implementation of Class TicTacToe. 1 /** 2 A 3 x 3 tic-tac-toe board. 3 */ 4 public class TicTacToe 5 6 private String[][] board; 7 private static final int ROWS = 3; 8 private static final int COLUMNS = 3; 9 /** 10 Constructs an empty board. 11 */ 12 public TicTacToe() board = new String[ROWS][COLUMNS]; 15 // Fill with spaces 16 for (int i = 0; i < ROWS; i++) 17 for (int j = 0; j < COLUMNS; j++) 18 board[i][j] = " "; /** 22 Sets a field in the board. The field must be unoccupied. i the row index j the column index player the player ("x" or "o") 26 */ 27 public void set(int i, int j, String player) if (board[i][j].equals(" ")) board[i][j] = player; /** 32 Creates a string representation of the board, such as 33 X O 34 X 35 O. the string representation 37 */ 38 public String tostring() String r = ""; 41 for (int i = 0; i < ROWS; i++) r = r + " "; 44 for (int j = 0; j < COLUMNS; j++) 45 r = r + board[i][j]; 46 r = r + " \n"; return r; Page 4/6

5 Question 3 continue a) You are required to add a method iswinner (String player) to Class TicTacToe. The method is called when one wants to check if a particular player has won the game or not. Recall that player X wins when they have a row, a column, or a diagonal of all X s characters. Similarly, player O wins when they have a row, a column, or a diagonal of all O s characters. [20 points] NOTE: Provide Documentation. /** checks if a player has won the player the player that may have won the true or false */ public boolean iswinner(string player) for (int i=0; i<rows; i++) int count=0; for (int j=0;j<columns; j++) if (player.equals(board[i][j])) if (count==columns) for (int j=0; j<columns; j++) int count=0; for (int i=0;i<rows; i++) if (player.equals(board[i][j])) if (count==rows) if(rows==columns) int count=0; for (int i=0; i<rows; i++) if (player.equals(board[i][i])) if (count==rows) count=0; for (int i=0, j=columns-1; i<rows; i++, j--) if (player.equals(board[i][j])) if (count==rows) return false; Page 5/6

6 Question 3 continue b) Now, complete the following runner program. The program should end when one of the players wins the game. [10 Points] 1 import java.util.scanner; 2 /** 4 This program runs a TicTacToe game. It prompts the 5 user to set positions on the board and prints out the 6 result. 7 */ 8 public class TicTacToeRunner 9 10 public static void main(string[] args) Scanner in = new Scanner(System.in); 13 String player = "X"; 14 TicTacToe game = new TicTacToe(); 15 while (!game.iswinner("x") &&!game.iswinner("o") ) System.out.print(game.toString()); 19 System.out.print( "Row for " + player); 21 int row = in.nextint(); 25 System.out.print("Column for " + player + ": "); 26 int column = in.nextint(); 27 game.set(row, column, player); 28 if (player.equals("x")) 29 player = "O"; 30 else 31 player = "X"; 33 // determine and print who is the winner O or X if (player.equals("x")) player = "o"; else player = "x"; System.out.println("Winner is: "+player); Page 6/6