McFarland School District

Problem Set 3: Loops

To complete this set of problems you must have gone through the following lessons:

All lessons for Problem Sets 1 & 2
Loops

Section 1: FOR LOOPS

Problem 1

Use a for loop to produce the following output.

Output Example

**********
**********
**********

Problem 2

Using only 1 asterisk and a for loop, produce the following output.

Output Example

****************************************

Problem 3

Use a for loop to produce the following output.

Output Example

Number of times looped: 1
Number of times looped: 2
Number of times looped: 3
Number of times looped: 4
Number of times looped: 5
Number of times looped: 6
Number of times looped: 7
Number of times looped: 8
Number of times looped: 9
Number of times looped: 10

Problem 4

Use a for loop to print all of the integers that end in 4 from 4 to 84.

Output Example

4 14 24 34 44 54 64 74 84

Problem 5

Use a for loop to print all of the integers from 99 down to 11 where both numbers are the same. The output should be as shown below.

Output Example

99 88 77 66 55 44 33 22 11

Problem 6

Use a for loop to produce the following output.

Output Example

10...9...8...7...6...5...4...3...2...1...Blastoff!

Problem 7

Write a program that will allow a number to be entered. Use the number as a step value, print the resulting numbers from 8 and 20.

Output Example

Enter the step value: 4
8 12 16 20

Problem 8

Use a for loop to produce the table portion (the bold selection) of the following output. (Hint: the value of x should start at 4 and end at 10)

Output Example

X     X^2     X^3
--------------------
4     16       64
6     36       216
8     64       512
10   100     1000

Problem 9

Using a for loop write a program that allows the ages of 3 persons to be entered, one at a time. The computer will then let them know if they are old enough to drive. Include the blank lines.

Output Example

Enter the age of person number 1: 12
You must wait 4 years to drive.

Enter the age of person number 2: 18
You can drive.

Enter the age of person number 3: 4
You must wait 12 years to drive.

Goodbye.

Problem 10

The Cheap Stay Motel has 25 rooms. Using a for loop have the computer print a label for each room's door indicating the room number.

Output Example

--------------------------
Cheap Stay Motel
       Room 1
--------------------------

--------------------------
Cheap Stay Motel
       Room 2
--------------------------

etc.... up to room...

--------------------------
Cheap Stay Motel
       Room 25
--------------------------

Problem 11

In a for loop have the computer generate 10 random numbers ranging from 1 to 10. The computer should print whether the numbers are less than 5, greater than 5 or equal to 5.

Output Example

On turn 1 the number 6 was chosen and found to be greater than 5.
On turn 2 the number 5 was chosen and found to be equal to 5.
...
On turn 10 the number 2 was chosen and found to be less than 5.

Problem 12

In a for loop have the computer randomly generate three numbers from 5 to 15. The output should be as shown below. Use a counter in the loop to calculate the total.

Output Example

The numbers chosen are: 7 12 6
The sum is 25.

Problem 13

Using a for loop write a program that finds the sum of the odd integers from 1 to 15. The output should be as shown below.

Output Example

The sum of 1+3+5+7+9+11+13+15 is 64

Problem 14

In a for loop have the computer randomly generate 1000 numbers from 0 to 9. The computer should print the total of numbers that were odd and the total that were even.

Output Example

There were 535 even numbers randomly chosen.
There were 465 odd numbers randomly selected.

Problem 15

Write a program that allows the user to enter a number. Have the computer calculate and print all the numbers that are factors of the number entered.

Output Example

Enter a positive whole number please: 12
The factors of 12 are 1 2 3 4 6 12

Section 2: WHILE LOOPS

Problem 16

Write a program that simulates the rolling of a pair of dice. The computer should keep on rolling until a 12 is rolled.

Output Example

Roll 1 = 5
Roll 2 = 7
Roll 3 = 12
A 12 was rolled, program terminated.

Problem 17

Write a program that asks for a name and a password and will not continue until the correct name and password are entered.

Output Example

Enter user name: Jim
Enter a password: dude
Either the user or password are incorrect, please try again.
Enter user name: Bob
Enter a password: tomato
Welcome Bob, you now have access to the file server.

Problem 18

Write a program that allows the computer to randomly select a number from 1 to 100. Have the user guess the number selected by the computer. The user should keep on guessing until the correct number is chosen. The output should be as shown below.

Output Example

Guess my number: 50
Too high.

Guess my number: 25
Too low.

Guess my number: 35
Too high.

Guess my number: 32
Correct!!

Problem 19

Modify the previous program so that the user is allowed only 6 guesses. The output should be as shown below.

Output Example

Guess my number, you have 6 guesses left: 75
Too low.
Guess my number, you have 5 guesses left: 90
Too high.
Guess my number, you have 4 guesses left: 85
Too low.
Guess my number, you have 3 guesses left: 86
Too low.
Guess my number, you have 2 guesses left: 89
Too high.
Guess my number, you have 1 guess left: 88
Too high.
Sorry, you lose. The number was 87.

Problem 20

Write a program that allows the user to input the numbers of times the computer should choose a random number ranging from 1 to 20. Restrict the entry from 3 to 8. The computer should print the numbers selected and a total as shown below.

Output Example

Enter a number from 3 to 8: 10
Invalid entry.
Enter a number from 3 to 8: 0
Invalid entry.
Enter a number from 3 to 8: 4

The numbers chosen are: 12 10 18 15
The total is 55.

Problem 21

Write a program that allows the user and computer to alternately select numbers from 3 to 12. The numbers are totaled after each entry. A winner is declared when the total is greater than 100. The last one to enter a number is the winner. Have the computer ask whether the user wishes to go first or second. The computer should disallow cheating.

Special Instructions: When solving a more complex problem such as this one it is a good idea to have a plan of attack. You must first break the large problem down into smaller parts. Begin the coding by working on each small part until it works correctly. Add more parts until the complete problem is solved.

This problem should be broken down into these parts:

Code for a simplified version of the game.
- Write the game code for a basic version of the game that does not include taking turns or playing again. Have the player enter a value and then have the computer take a turn. Use a while loop so the game continues until the total value exceeds 100.
Code to prevent cheating.
- Add a while loop around the code that allows the player to enter a value. The loop should be written so that the game only accepts values from 3 to 12 too be used.
Code for starting first or second.
- Before the code of the game write code that asks the user whether he/she would like to go first or second. Place a while loop around the code so that only the values 1 or 2 are accepted as valid entries.
- Change the code of the game so that it can alternate turns. You will need to use If to separate the user's turn from the computer's.

Output Example

Would you like to go first or second? (Enter 1 or 2): 1
Enter your choice (3-12): 10
The total is now 10
I choose 3
The total is now 13
Enter your choice (3-12): 10
The total is now 23
I choose 8
The total is now 31
...
The total is now 92.
Enter your choice (3-12): 10
The total is now 102
You have won!!!
Would you like to play another round? (Y/N): N
Goodbye.

Section 3: NESTED LOOPS

Problem 22

Using only 1 question mark and a nested for loop have the computer print a rectangle consisting of five lines of twenty question marks each.

Output Example

????????????????????
????????????????????
????????????????????
????????????????????
????????????????????

Problem 23

Modify the previous program so that the user can enter the number of rows, the number in each row and the letter to use.

Output Example

Enter the number of rows: 2
Enter the width of the row: 5
Enter the letter to use: H

HHHHH
HHHHH

Problem 24

Write a program that uses nested for loops to produce the following output.

Output Example

&
&&
&&&
&&&&
&&&&&

Problem 25

Modify the previous program to produce the following output.

Output Example

&&&&&
&&&&
&&&
&&
&

Problem 26

Use nested loops to produce the following output.

Output Example

The value of the outside loop is 1
    The value of the inside loop is 1
    The value of the inside loop is 2
    The value of the inside loop is 3
The value of the outside loop is 2
    The value of the inside loop is 1
    The value of the inside loop is 2
    The value of the inside loop is 3
The value of the outside loop is 3
    The value of the inside loop is 1
    The value of the inside loop is 2
    The value of the inside loop is 3

Problem 27

Write a program that uses nested for loops to produce the following output.

Output Example

X=20
Y=1 Y=2 Y=3
X=21
Y=1 Y=2 Y=3
X=22
Y=1 Y=2 Y=3
X=23
Y=1 Y=2 Y=3
X=24
Y=1 Y=2 Y=3

Problem 28

Write a program that calculates and prints all of the possible combinations of coins that add up to 50 cents using quarters, dimes and nickels.

Output Example

Quarters	Dimes	Nickels
0	0	10
0	1	8
... some results omitted to save space ...
2	0	0

Problem 29

Modify the previous program so that it includes 50 cent pieces and the coins must total one dollar.

Output Example

Half Dollars	Quarters	Dimes	Nickels
0	0	0	20
0	0	1	18
... some results omitted to save space ...
2	0	0	0

Problem 30

Write a program that uses nested for loops to calculate the factorials of the numbers 1 through 10. (Hint: the factorial of 5, shown as 5!, is 1*2*3*4*5)

Output Example

1! Is 1
2! Is 2
3! Is 6
4! Is 24
5! Is 120
6! Is 720
7! Is 5040
8! Is 40320
9! Is 362880
10! Is 3628800

Problem 31

Using nested for loops write a program that finds all of the prime numbers from 1 to 50.

Output Example

The prime numbers are: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

Set 3: Loops

McFarland High (9-12)