Monthly Archives: September 2013

Mazes 2

Mazes #2

Shunya Map 1


Shunya 4




Struhl Map:

  • Start   20, 18
  • go around the interior, get the flower, pick it up.
  • 1 loop only




Heeyeon’s Map:

  • heeyeons_maze.jev
  • start Jeroo at (23,1) and pick up the flower  at that location
  • go to (1,23)
  • you may NOT pick a flower or visit a cell that has a flower (See animation at bottom)

Picture at start:


One Solution:heeyeons_maze


Brett’s Maze 2

Description: Start at 0,0, pick all the flowers then use them to toss() your way through the nets.   bretts-maze2


George’s Map  : Start at ( 10,0) , facing SOUTH,  Use 1 loop and pick the flowergeorges-map

 Paul’s Diagonal Map


 Matt’s All Flower Map
Map name :   matt_water_flower_map.jev
Directions: pick up all the flowers. Use 1 while loop. You can start and end wherever you want. Just make sure that the loop eventually terminates.
One strategy:

A Different strategy


Jar jar’s Haven:



Bismark’s Map

Directions: Pick all the flowers. Start anywhere ; end anywhere. Don’t die, Make sure the loop ends.



Diagonal Inwards
Fill up the Map
  • * Use a blank map and have 2 Jeroos fill up every spot with a flower.
  • Use a single loop (not an infinite one either)




Mazes 1

Objective: To use while loops to get the Jeroo to pass through each maze and get the flower. It is possible to write a solution to both of these mazes using a single while loop–albeit this loop will have several( about 5 or 6) if tests! It is important for this problem that you do NOT simply hand code this. To get an A on both of these assignments you must use 1 single while loop per maze.
Download All Island Files



Shunya 3



Aliya’s Map


 Mazes 2 (start in top left, 1 loop to pick flower)



Shunya 2



Yuna’s Original Maze





 island-3-D (start in the top left, and get to the bottom right)




4) ZigZag   : Use 1 while loop (not infinite), follow the flowers, picking them up and use those flowers traverse over the nets. Notice where the Jeroo ends (ie your while loop condition)


5)  Spell Z (Blank Map)

  1. start at 0 , 0 with 70 flowers.
  2. Use a single while loop to spell a letter z



Last and most definitely not least:

island3-C ** A+ assignment.

This is the deceptively hard and should be done last and only if you want that A+



Done all of the maps? Start on the next set here

Systematically Visit All Cells [Java]

Description: It’s harvest time and Adam must pick all of the flowers on the island. Unfortunately for Adam, he doesn’t know where the flowers are growing. Flowers could be growing anywhere on the island. In order to keep from being too exhausted, he can only visit each cell once, and he cannot try to pick from an empty cell. There are no nets, water features, or other Jeroos on the island. The purpose of this program is to find a systematic way for Adam to visit every cell exactly once, and pick the flowers from the cells that have flowers.
Download all the island files

The Maps

Note: Do not be fooled by how similar the next map is. You will probably have to rewrite some code to complete the next one.

Extra Credit Java Arrays Question

Extra Credit (GOOD LUCK!)


Note first try addition , also worth some (though less) extra credit.

** int[] multiply(int[] num1, int[] num2, int base) throws ArithmeticException

@precondition 1 < base < 11
@precondition num1.length = 5 and num2.length = 5
@postcondition: the returned array has 5 elements representing the product or an ArithmeticException is thrown

Description: This method attempts to replicate multiplication. Both num1 and num2 represent five digit numbers. Each element in the array stores one of the digits. For instance, the number 143 would be represented as {0,0,1,4,3 }. Numbers can be in any base between 2 and 10 inclusive , and the number 101102 in binary would appear in an arrays as : {1, 0, 1 , 1, 0 } . Let’s assume the numbers are positive. You should return an array representing the digits of the product of num1 and num2. If the number of digits in the product exceeds the maximum number of digits (5) , you should throw an arithmetic exception as shown in the code below:

Note: You may not use any kind of helper or utility methods that are built into pre-defined Java classes for converting numbers between bases. Only use techniques taught in this class.

Method Call return value/output
multiply ( {0,0,0 , 4,2},{0,0,0,5,1}, 10)   {0 , 2 ,  1 ,  4 ,  2}    (42 *51= 2142)
multiply ( {0,0,0, 3,1} , { 0 ,0,0,2,4}, 10) {0 , 0 ,  7 , 4 ,  4}    (31 *24= 744)
multiply ( {6,5,1, 3,1} , { 0 ,0,0,2,4}, 10) throw an ArithmeticException

Tool for checking work

Use programmers calc to check your work. This is an awesome 64 calculator and you can multiply in binary, decimal or octal to help you see if you did your work correctly.


Objective: A Jeroo starts at the southwest corner of the island, location (23,0), facing East with no flowers. There is a flower somewhere east of the Jeroo. There are zero or more hurdles, represented by nets, between the Jeroo and the flower. Each hurdle is a rectangular arrangement of nets with its base along the Southern Sea. The height and width of each hurdle is unknown. The number of hurdles and the spacing between the hurdles is unknown. There is at least one row of empty cells along the top and sides of each hurdle. There are no water features and no other Jeroos on the island. The only nets are those that define the hurdles. The goal of this program is to have the Jeroo jump all of the nets, pick the flower, and stop. A representative island is shown in figure 1.

  • start at bottom left
  • with zero flowers
  • use a single while loop
  • you may only hop() a single space (ie no hop(2), hop(3), hop(n) )
  •  pick the flower that is (generally) located on the right


Download all the island files


Solution : Not graded

two-hurdles.jev Not graded



Not graded


Extreme Hurdles.jev    8/10

Description:Write an infinite loop that makes your Jeroo travel around the perimeter of the island.  9/10

 Download this island file (steve’s maze)

steves maze


download-bttnJacob Icejet’s Map

  • this gets you the 10/10
  • use 1 while loop
  • the Jeroo should travel in an infinite loop around the perimeter of the map.





download-bttnjacob_icejet_map2 Extra credit

  • this is extra credit
  • 1 while loop
  • start with zero flowers
  • pick the one flower in the top right and use that to access the flower that is in the bottom middle.


Two Friends Meet

One Saturday morning, two friends, Bugs and Daffy, decide to meet and plant flowers to beautify Santong island. Daffy starts in the Northwest corner facing East with 90 flowers in his pouch. Bugs starts in the Northeast corner facing West with 90 flowers in his pouch. Bugs and Daffy begin hopping toward one another. As they hop, each plants exactly one flower at every location it enters, including its starting location. They meet, facing each other, roughly in the middle of row 0. After a handshake and a little small talk, Bugs and Daffy both turn toward the south and continue planting flowers all the way to the southern edge of the island. When both reach the South Sea, the say goodbye and part. Daffy turns west and plants flowers all the way to the Western Ocean. Bugs turns east and plants flowers all the way to the Eastern Ocean. This is where our story ends. Your task is to write a Jeroo program that will illustrate this story.

One possible solution to this project is represented in the picture below

Luhn Check Assignment

Luhn Check

It is possible to tell if a number could be a valid credit card. Credit cards numbers can be validated against an algorithm known as a Luhn.  Read this first.

Luhn Number Generator

Counting from the check digit, which is the rightmost, and moving left, double the value of every second digit.

Sum the digits of the products together with the undoubled digits from the original number.

If the total ends in 0 (put another way, if the total modulo 10 is congruent to 0), then the number is valid according to the Luhn formula; else it is not valid.


from :

from :

Image from

Mod 10+5 Variant Some credit cards use the “Mod 10 plus 5” variant to extend the space of valid card numbers.[citation needed] In this variant, if the sum ends in 0 or 5, the number is considered valid.






A more extensive analysis with good images and an online Luhn Checker  (currently blocked by Harrison network filter)

Jeroo Walk The Lake with Loops


Original Project Descriptions is here

Acknowledgement This problem is adapted from one that was created originally by Erica Eddy of The University of Wisconsin – Parkside.

Your jeroo is exploring the outer perimeter of the lake. It starts next to a flower and travels the entire way around the lake. Have your jeroo stop immediately before the flower (using a loop) and then, after the loop is over,  your jeroo should pick the flower.

Downloaddownload-bttn the maps

Map #1 : rectangular-lake.jev arrow_right_large
recangular-lake-if2.jev arrow_right_large  
For this one, your Jeroo should travel around the entire outer rim of the island and stop immediately before the flower.
Remember Nets kill Jeroosrectangular-lake-bumps2.jev arrow_right_large  
Write a loop that makes the jeroo travel around the lake below. This loop should never end. walk-the-lake-jacks-map.jevs

Printing Digits Of Numbers in Java Assignment

Let’s write the following method

public void printDigits( int n){



Walk through of how the code should work:

the algorithm inolves

1) extract last digit

2) print last digit

3) remove last digit

keep doing this until there are no more digits


Example :

Let’s look at printDigits( 345)

Walk through of how the code should work:

the algorithm inolves

1) extract last digit ‘5’

2) print last digit print ‘5’

3) remove last digit now n should be ’34’

do this for ‘4’ and then ‘3’ until there are no more digits

You need a while loop. Think about it. What is the value of n when there are no more digits?