Programming Assignment 8

Due: Week of Mar. 20 before lab

1. (25 points) Problem 7.3 of the book. Count occurrence of numbers. Write a program that reads the integers between 1 and 100 and counts the occurrences of each. Assume the input ends with 0. Note that if a number occurs more than one time, the plural word "times" is used in the output. You must use an array in this problem, no other container can be used, e.g., ArrayList.
   • Name the file and program ch7pr3.java.
   • Example execution (java ch7pr3) user provides input:
     
     Enter the integers between 1 and 100: 2 5 6 4 3 23 43 2 0
     2 occurs 2 times
     3 occurs 1 time
     4 occurs 1 time
     5 occurs 1 time
     6 occurs 1 time
     23 occurs 1 time
     43 occurs 1 time
2. (25 points) Problem 7.25 of the book. Algebra: solve quadratic equation. Write a method for solving a quadratic equation using the following header:
   public static int solveQuadratic(double[] eqn, double[] roots);
   The coefficients of a quadratic equation ax2 + bx + c = 0 are passed to the array eqn and the real roots are stored in roots. The method returns the number of real roots. Write a program that prompts the user to enter values for a, b, and c and displays the number of real roots and all real roots.
   • Name the file and program ch7pr25.java.
   • Example execution (java ch7pr25) user provides input:
     
     Enter values for a, b, and c of ax^2 + bx + c = 0: 5.4 6.2 1.5
     5.400000x^2 + 6.200000x + 1.500000 = 0 has 2 real roots.
     Real root 0: x = -0.346515
     Real root 1: x = -0.801633
   • Example execution (java ch7pr25) user provides input:
     
     Enter values for a, b, and c of ax^2 + bx + c = 0: 5 2 1
     5.000000x^2 + 2.000000x + 1.000000 = 0 has 0 real roots.
   • Example execution (java ch7pr25) user provides input:
     
     Enter values for a, b, and c of ax^2 + bx + c = 0: -3 -24 -48
     -3.000000x^2 + -24.000000x + -48.000000 = 0 has 1 real roots.
     Real root 0: x = -4.000000
3. (25 points) Problem 7.27 of the book. Identical arrays. The arrays list1 and list2 are identical if they have the same contents. Write a method that returns true if list1 and list2 are identical, using the following header:
   public static boolean equals(int[] list1, int[] list2);
   Write a test program that prompts the user to enter two lists of integers and displays whether the two are identical. Note that the first number in the input indicates the number of the elements in the list. This number is not part of the list. You are allowed to use Array.sort, but at least consider trying to think of how to solve it without that function.
   • Name the file and program ch7pr27.java.
   • Example execution (java ch7pr27) user provides input:
     
     Enter list1: 5 2 5 6 6 1
     Enter list2: 5 5 2 6 1 6
     Two lists are identical
   • Example execution (java ch7pr27) user provides input:
     
     Enter list1: 5 5 5 6 6 1
     Enter list2: 5 2 5 6 1 6
     Two lists are not identical
4. (25 points) Problem 7.31 of the book. Merge two sorted lists. Write the following method that merges two sorted lists into a new sorted list.
   public static int[] merge(int[] list1, int[] list2);
   Implement the method in a way that takes at most list1.length + list2.length comparisons. Write a test program that prompts the user to enter two sorted lists and displays the merged list. Note that the first number in the input indicates the number of the elements in the list. This number is not part of the list. You cannot use Arrays.sort().
   • Name the file and program ch7pr31.java.
   • Example execution (java ch7pr31) user provides input:
     
     Enter list1: 5 1 5 16 61 111
     Enter list2: 4 2 4 5 6
     The merged list is 1 2 4 5 5 6 16 61 111
5. Bonus. (20 points) Problem 7.35 of the book. Game: hangman. Write a hangman game that randomly generates a word and prompts the user to guess one letter at a time, as shown in the sample run. Each letter in the word is displayed as an asterisk. When the user makes a correct guess, the actual letter is then displayed. When the user finishes a word, display the number of misses and ask the user whether to continue to play with another word. Declare an array to store words as follows:
   
   // Add any words you wish in this array
   String[] words = {"write", "that", "program"};
   • Name the file and program ch7pr35.java.
   • Example execution (java ch7pr35) user provides input:
     
     (Guess) Enter a letter in word ******* > p
     (Guess) Enter a letter in word p****** > r
     (Guess) Enter a letter in word pr**r** > p
          p is already in the word
     (Guess) Enter a letter in word pr**r** > o
     (Guess) Enter a letter in word pro*r** > g
     (Guess) Enter a letter in word progr** > n
          n is not in the word
     (Guess) Enter a letter in word progr** > m
     (Guess) Enter a letter in word progr*m > a
     The word is program. You missed 1 time
     Do you want to guess another word? Enter y or n> n