CompSci 94 Test 2 Practice April 2018 Solutions
 
1 A)
There are three events. 

1 Scene Activated Listener
2 Time Elasped Listeners

1B) 
MyFirstMethod - handles the sceneActivatedListener event

First TimeElapsedListener - handled by an if statement if the hare and
tortoise are less than 1.0 apart and this event currently isn't being
handled, it also calls the procedure something 

Second TimeElapsed Listener - handed by an if statement if the hare and
tortoise are about 1.0 or further apart - then the penguin turns to face
the hare, and moves over to it and then says hello

1C)
Since the penquin and hare are far apart, the penguin turns to face the
hare and repeatedly moves closer to it, stopping close to it and says
hello. 

1D) A) Move the tortoise to the table. 

Nothing else happens.

1D) B) Move the penguin to the table

The penguin turns to face the hare, and tries to move over to it. But note
that the penguin may be turning still as we move the penguin to the table,
so that when it starts moving forward, it may not be facing the hare
anymore and may pass by the hare and keep going.

1D) C) Move the hare to the table

The penguin turns to face the hare and tries to move over to it.  But note
that the penguin may be turning still as we move the hare to the table,
so that when it starts moving forward, it may not be facing the hare
anymore and may pass by the hare and keep going.


2) 
The panda says a random number from 0 to 5. Then the characters in the
array move up that amount one at a time. Then the object in the index
position that is the random number, that object turns around once. 

3) A) 

Rewrite mouseClicked to:

if getModelAtMouseLocation == soccerball
    updateScore increment 1
else
   if getModelAtMouseLocation == volleyball
      updateScore increment 2
   else
      // must be pumpkinHead
      updateScore increment 5

3B) 
The game will run the same except now when you click on volleyball you will
get 3 pts added to the score, 2 from one event and 1 pt from the new
event. 

 
4A)
declare WholeNumber function numberVisible
WholeNumber count = 0
for each Flyer onePenguin in penguins
    if onePenguin getOpacity > 0.5 is true then
        count = count + 1
return count

 
4B)
declare procedure makeInvisible
WholeNumber randomIndex = 
                  nextRandomIngegerFromAUpToButExcludingB 0, penguins.length 

// need to make sure the penguin at the randomIndex location is visible. If
// not, we need to generate another randomIndex 
while penguins[randomIndex] getOpacity < 0.5 is true
    // That penguin is already invisible, generate another randomIndex
    randomIndex = nextRandomIntegerFromAUpToButExcludingB 0, penguins.length
loop

// at this point, randomIndex should be the location of a penguin that is
// visible, say. make that penguin invisible now!!
penguins[randomIndex] setOpacity 0.0

  

4C)
declare procedure MakeAllButNumInvisible WholeNumber number
while numbervisible > number
    makeInvisible


5A) 
declare WholeNumber function numberOfTypeBird Flyer birdType

WholeNumber birdCount = 0
For each Flyer oneBird in birds
   if oneBird toString startsWith birdType toString is true then
        birdCount = birdCount + 1
Return birdCount 


5B) 

declare WholeNumber function indexLocationOfBird,  Flyer oneBird

WholeNumber index = 0
for each Flyer aBird in birds
    if aBird toString startsWith oneBird toString is true then
        return index
    index = index + 1
loop

// Should never get here, you should return for some position in the array
// This last return is just in case, even though 
return 0


5C)

declare procedure changeBirdInArray Flyer birdOne, Flyer birdTwo
for each Flyer someBird in birds
    if someBird toString contentEquals birdOne toString is true then
        birds[indexLocationOfBird birdOne] = birdTwo