Spring Semester 2002

Iffy Practice Problems: This is textbook chapter 5. Programming problems.
 1. Write a program (called `One`) that prints all real solutions to the quadratic equation a x2 + b x + c = 0 Read in a, b, c and use the quadratic formula. If the discriminant b2 - 4ac is negative, display a message stating that there are no real solutions. Here's how your program should behave: ```frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 1.0 Please enter the value of b then press Enter : -2.0 Please enter the value of c then press Enter : 1.0 2.0 2.0 frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : 0 Please enter the value of c then press Enter : 1 There are no solutions. frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : 2 Please enter the value of c then press Enter : 3 There are no solutions. frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : -3 Please enter the value of c then press Enter : 1 1.881966011250105 4.118033988749895 frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 0 Please enter the value of b then press Enter : 0 Please enter the value of c then press Enter : 3 3.0 is not zero frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : 0 Please enter the value of c then press Enter : 0 -0.0 0.0 frilled.cs.indiana.edu%java One Please enter the value of a then press Enter : 0 Please enter the value of b then press Enter : 0 Please enter the value of c then press Enter : 0 Identity: zero == zero. frilled.cs.indiana.edu%```

2. Write a program (called `Two`) that takes user input describing a playing card in the shorthand notation described below, and then prints the full description of the card.
 A Ace 2..10 Card values J Jack Q Queen K King
 D Diamonds H Hearts S Spades C Clubs
Here's a sample run of such a program:
```frilled.cs.indiana.edu%java Two
Enter the card notation: AS
frilled.cs.indiana.edu%java Two
Enter the card notation: 2H
Two of hearts.
frilled.cs.indiana.edu%java Two
Enter the card notation: CJ
Unknown denomination of unknown colour.
frilled.cs.indiana.edu%java Two
Enter the card notation: JC
Jack of clubs.
frilled.cs.indiana.edu%java Two
Enter the card notation: QK
Queen of unknown colour.
frilled.cs.indiana.edu%java Two
Enter the card notation: QH
Queen of hearts.
frilled.cs.indiana.edu%java Two
Enter the card notation:  A D
Unknown denomination of unknown colour.
frilled.cs.indiana.edu%java Two
Enter the card notation: A D
Ace of unknown colour.
frilled.cs.indiana.edu%java Two
Ace of diamonds.
frilled.cs.indiana.edu%```

 3. Write a program (called `Three`) that reads in three floating-point numbers and prints the largest of the three inputs Here are (essentially) all possible runs of your program: ```frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : 2 Please enter the value of c then press Enter : 3 The largest number is: 3.0 frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 1 Please enter the value of b then press Enter : 3 Please enter the value of c then press Enter : 2 The largest number is: 3.0 frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 2 Please enter the value of b then press Enter : 1 Please enter the value of c then press Enter : 3 The largest number is: 3.0 frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 2 Please enter the value of b then press Enter : 3 Please enter the value of c then press Enter : 1 The largest number is: 3.0 frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 3.0 Please enter the value of b then press Enter : 1.0 Please enter the value of c then press Enter : 2.0 The largest number is: 3.0 frilled.cs.indiana.edu%java Three Please enter the value of a then press Enter : 3.0 Please enter the value of b then press Enter : 2.0 Please enter the value of c then press Enter : 1.0 The largest number is: 3.0 frilled.cs.indiana.edu%```

 4. Write a program (called `Four`) that creates a circle with radius 100 and center (110, 120). Ask the user to specify the x and y coordinates of a point. If the point lies inside the circle, then show a message "Congratulations!" Otherwise, show a message "You missed." Feel free to use, and enhance with a method `public boolean contains(double xPoint, double yPoint){ ... }` the `Circle` class that we developed in the second set of problems. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Four Welcome. Circle created. Center is at: (110.0, 120.0) Radius is: 100.0 You will be asked to specify a point. First enter x, then enter y. Please enter x now: 110 Please enter y now: 120 Congratulations. frilled.cs.indiana.edu%java Four Welcome. Circle created. Center is at: (110.0, 120.0) Radius is: 100.0 You will be asked to specify a point. First enter x, then enter y. Please enter x now: -30 Please enter y now: 120 You missed. frilled.cs.indiana.edu%java Four Welcome. Circle created. Center is at: (110.0, 120.0) Radius is: 100.0 You will be asked to specify a point. First enter x, then enter y. Please enter x now: 170.98 Please enter y now: 190.05 Congratulations. frilled.cs.indiana.edu%```

 5. Write a program (called `Five`) that asks the user to specify the radii of two circles. The first circle has center (100, 200) and the second circle has center (200, 100). Check to see if the circles intersect. If they intersect, then display a message "Circles intersect." Otherwise, display "Circles don't intersect." Hint: Compute the distance between the centers and compare it to the radii. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 10 Great. Now please specify the radius of the second circle: 10 Circles don't intersect. frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 100 Great. Now please specify the radius of the second circle: 100 Circles intersect. frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 70 Great. Now please specify the radius of the second circle: 71.42 Circles don't intersect. frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 70 Great. Now please specify the radius of the second circle: 71.43 Circles intersect. frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 140 Great. Now please specify the radius of the second circle: 1.414299 Circles don't intersect. frilled.cs.indiana.edu%java Five Welcome. Please specify the radius of the first circle: 140 Great. Now please specify the radius of the second circle: 1.4299 Circles intersect. frilled.cs.indiana.edu%```

 6. Write a program (called `Six`) that prints the question Do you want to continue? and reads the user input. If the user input is any of the following: Y Yes OK Sure Why not? print out OK If the user input is N No then print out Terminating Otherwise, print Bad input The case of the user input should not matter. For example, y yes are also valid inputs. Hint: Convert the user input to lowercase and then compare. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Six Do you want to continue? Y OK frilled.cs.indiana.edu%java Six Do you want to continue? Yes OK frilled.cs.indiana.edu%java Six Do you want to continue? OK OK frilled.cs.indiana.edu%java Six Do you want to continue? suRe OK frilled.cs.indiana.edu%java Six Do you want to continue? Sure OK frilled.cs.indiana.edu%java Six Do you want to continue? whY nOt? OK frilled.cs.indiana.edu%java Six Do you want to continue? why not ? Bad input frilled.cs.indiana.edu%java Six Do you want to continue? N Terminating frilled.cs.indiana.edu%java Six Do you want to continue? NO Terminating frilled.cs.indiana.edu%java Six Do you want to continue? nO Terminating frilled.cs.indiana.edu%java Six Do you want to continue? No! Bad input frilled.cs.indiana.edu%```

 7. Write a program (called `Seven`) that translates a letter grade into a number grade. Letter grades are `A`, `B`, `C`, `D`, `F` possibly followed by `+` or `-`. Their numeric values are 4, 3, 2, 1, and 0. There is no `F+` or `F-`. A `+` increases the numeric value by 0.3, a `-` decreases it by 0.3. However an `A+` has a value of 4.0. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Seven Enter a letter grade: A+ The numeric value is: 4.0 frilled.cs.indiana.edu%java Seven Enter a letter grade: A + Bad input. frilled.cs.indiana.edu%java Seven Enter a letter grade: U- Bad input. frilled.cs.indiana.edu%java Seven Enter a letter grade: B- The numeric value is: 2.7 frilled.cs.indiana.edu%java Seven Enter a letter grade: C The numeric value is: 2.0 frilled.cs.indiana.edu%java Seven Enter a letter grade: F The numeric value is: 0.0 frilled.cs.indiana.edu%java Seven Enter a letter grade: D- The numeric value is: 0.7 frilled.cs.indiana.edu%java Seven Enter a letter grade: -- Bad input. frilled.cs.indiana.edu%```

 8. Write a program (called `Eight`) that translates a number between 0 and 4 into the closest letter grade. For example, the number 2.8 (which might have been the average of several grades) would be converted to `B-`. Break ties in favor of the better grade; for example 2.85 should be a `B`. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 3.85 A frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 3.84 A- frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 3.5 A- frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 3.49 B+ frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 3.1 B frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : 10 A+ frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : -2 frilled.cs.indiana.edu%java Eight Enter numeric score then press Enter : -0.5 frilled.cs.indiana.edu%```

 9. Write a program (called `Nine`) that reads in three strings and sorts them lexicographically. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Nine Enter three strings: Alpha Beta Gamma Alpha Beta Gamma frilled.cs.indiana.edu%java Nine Enter three strings: Alpha Gamma Beta Alpha Beta Gamma frilled.cs.indiana.edu%java Nine Enter three strings: Username User Use Use User Username frilled.cs.indiana.edu%java Nine Enter three strings: Alpha Alpha Alpha Alpha Alpha Alpha frilled.cs.indiana.edu%java Nine Enter three strings: Gamma gamma gama Gamma gama gamma frilled.cs.indiana.edu%java Nine Enter three strings: 10 1 2 1 10 2 frilled.cs.indiana.edu%```

 10. A year with 366 days is called a leap year. A year is a leap year if it is divisible by 4 (for example, the year 1980), except it is not a leap year if it is divisible by 100 (for example, the year 1900); however, it is a leap year if it is divisible by 400 (for example, the year 2000). There were no exceptions before the introduction of the Gregorian calendar on October 15, 1582 (for example, the year 1500 was a leap year). Write a program (called `Ten`) that asks the user for a year and computes whether that year is a leap year or not. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Ten Please enter the year then press Enter : 1500 Leap year: 1500 frilled.cs.indiana.edu%java Ten Please enter the year then press Enter : 1900 1900 not a leap year! frilled.cs.indiana.edu%java Ten Please enter the year then press Enter : 1996 Leap year: 1996 frilled.cs.indiana.edu%java Ten Please enter the year then press Enter : 1997 1997 not a leap year! frilled.cs.indiana.edu%java Ten Please enter the year then press Enter : 2000 Leap year: 2000 frilled.cs.indiana.edu%```

 11. Write a program (called `Eleven`) that asks the user to enter a month 1 = January 2 = February ... and so on and then prints the number of days of the month. For February, print `28 or 29 days` Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Eleven Enter a month : 1 31 days frilled.cs.indiana.edu%java Eleven Enter a month : 2 28 or 29 days frilled.cs.indiana.edu%java Eleven Enter a month : 3 31 days frilled.cs.indiana.edu%java Eleven Enter a month : 4 30 days frilled.cs.indiana.edu%java Eleven Enter a month : 5 31 days frilled.cs.indiana.edu%java Eleven Enter a month : 12 31 days frilled.cs.indiana.edu%java Eleven Enter a month : 13 Bad input frilled.cs.indiana.edu%java Eleven Enter a month : 0 Bad input frilled.cs.indiana.edu%java Eleven Enter a month : 1.2 Exception in thread "main" java.lang.NumberFormatException: 1.2 at java.lang.Integer.parseInt(Integer.java:418) at java.lang.Integer.parseInt(Integer.java:458) at ConsoleReader.readInt(Eleven.java:58) at Eleven.main(Eleven.java:7) frilled.cs.indiana.edu%```

 12. Write a program (called `Twelve`) that reads in two floating-point numbers and tests BOTH whether they are the same up to two decimal places, and whether they are within 0.01 of each other Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Twelve Comparing floating-point numbers. Enter the first number : 1.3456 Enter the second number: 1.3402 1.3456 and 1.3402 are the same up to two decimal places. 1.3456 and 1.3402 are within 0.01 of one another. Thanks for asking. frilled.cs.indiana.edu%java Twelve Comparing floating-point numbers. Enter the first number : 2.003 Enter the second number: 1.998 2.003 and 1.998 are NOT the same up to two decimal places. 2.003 and 1.998 are within 0.01 of one another. Thanks for asking. frilled.cs.indiana.edu%java Twelve Comparing floating-point numbers. Enter the first number : 1.998 Enter the second number: 1.990 1.998 and 1.99 are the same up to two decimal places. 1.998 and 1.99 are within 0.01 of one another. Thanks for asking. frilled.cs.indiana.edu%java Twelve Comparing floating-point numbers. Enter the first number : 1.0000001 Enter the second number: 0.9999999 1.0000001 and 0.9999999 are NOT the same up to two decimal places. 1.0000001 and 0.9999999 are within 0.01 of one another. Thanks for asking. frilled.cs.indiana.edu%```

 13. Enhance the `BankAccount` class by rejecting negative amounts in the `deposit` and `withdraw` methods rejecting withdrawals that would result in a negative balance Write a program (called `Thirteen`) that illustrates the behaviour of your new `BankAccount`. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Thirteen Hello, and welcome to JavaOne Bank. An account will be created for you. What will the initial balance be? Type it now: 20 The current balance in your account is: 20.0 You now want to make a deposit. How much? Type the amount here: 30 The current balance in your account is: 50.0 You now want to make a withdrawal. How much? Type it now: 100 Sorry, you cannot do that. The current balance in your account is: 50.0 Thanks for using class BankAccount. Good-bye! frilled.cs.indiana.edu%java Thirteen Hello, and welcome to JavaOne Bank. An account will be created for you. What will the initial balance be? Type it now: -20 The current balance in your account is: -20.0 You now want to make a deposit. How much? Type the amount here: 10 The current balance in your account is: -10.0 You now want to make a withdrawal. How much? Type it now: 10 Sorry, you cannot do that. The current balance in your account is: -10.0 Thanks for using class BankAccount. Good-bye! frilled.cs.indiana.edu%java Thirteen Hello, and welcome to JavaOne Bank. An account will be created for you. What will the initial balance be? Type it now: -30 The current balance in your account is: -30.0 You now want to make a deposit. How much? Type the amount here: -20 Sorry, you cannot do that. The current balance in your account is: -30.0 You now want to make a withdrawal. How much? Type it now: -40 The current balance in your account is: 10.0 Thanks for using class BankAccount. Good-bye! frilled.cs.indiana.edu%``` Notice that you are free to allow negative initial balances (resembling a loan) but the two methods that implement deposit and withdraw should behave as stated in the text of the problem (rejecting negative arguments and rejecting operations that result in a negative balance other than the initial creation of the account). If you want you can disallow initial negative balances as well.

 14. Write a program that reads in the name and hourly wage of an employee. Then ask how many hours the employee worked in the past week. Be sure to accept fractional hours. Compute the pay. Any overtime work (over 40 hours per week) is paid at 150 percent of the regular wage. Print a paycheck for the employee. Here's a sample run of such a program: ```frilled.cs.indiana.edu%java Fourteen Please enter employee's name then press Enter : Larry Bird Please enter hourly wage then press Enter : 12.50 Please enter hours worked then press Enter: 10 Paycheck for employee Larry Bird Hours worked: 10.0 Hourly wage: 12.5 Total payment: 125.0 frilled.cs.indiana.edu%java Fourteen Please enter employee's name then press Enter : Michael Jordan Please enter hourly wage then press Enter : 10 Please enter hours worked then press Enter: 50 Paycheck for employee Michael Jordan Hours worked: 50.0 Hourly wage: 10.0 Overtime hours: 10.0 Overtime hourly wage: 15.0 Total payment: 550.0 frilled.cs.indiana.edu%java Fourteen Please enter employee's name then press Enter : Dennis Rodman Please enter hourly wage then press Enter : 2 Please enter hours worked then press Enter: -4 Paycheck for employee Dennis Rodman Hours worked: -4.0 Hourly wage: 2.0 Total payment: -8.0 frilled.cs.indiana.edu%``` Notice it's up to you what you do when the input is out of range. Also, you don't need to use the class `Employee` developed in the previous chapter, the emphasis is here on decisions.

Last updated: Feb 5, 2002 by Adrian German for A201