CS305J Fall 2007

Final Key, Suggested Solutions, and Grading Criteria

Abbreviations:

NAP - no answer provided
ECF - error carried forward
OBOE - off by one error
BOD - benefit of the doubt
GCE - misunderstood question. Answer is way off base.

1. Answer as shown or -1. If mistake on data type, error carried forward to next
answers.

1. 	13
2. 	2
3. 	"3UT"
4.	1.0
5.	1.5
6.	2
7.	"Long52"
8.	false 	// on booleans differences in capitalization okay
9.	true
10.	false


2. 0.5 point each. No error carried forward.

		result == -1	i < nums.length		nums[i] > tgt	result == i
Point A		A				S					X				N

Point B		A				A					S				N

Point C		N				A					A				A

Point D		S				A					S				S

Point E		S				N					X				S


3. Suggested Solution:

public static boolean okToRide(int temp, int timeOfDay, boolean isRaining){
	boolean result = false;
	if( 6 <= timeOfDay && timeOfDay <= 18){
		if(!isRaining && 30 < temp && temp < 110)
			result = true;
		else if(isRaining && 70 < temp && temp < 115)
			result = true;
	}
	return result;
}

Different answers acceptable if they work.

check time of time in bounds, attempt: 1 point, correct 3 points
check temp when not raining, attempt 1 point, correct 2 points
check temp when not raining, attempt 1 point, correct 2 points
return answer 1 point



5. Suggested Solution:

public  class Badger implements Critter{
	private static final int[] WEAPONS = {Critter.ROCK, Critter.PAPER,
	Critter.SCISSORS};

	private Color myColor;
	private int numFights;
	private int weapon;

	public Badger(){
		double r = Math.random();
		if( r < 0.6 )
			myColor = Color.BLACK;
		else if( r < 0.9 )
			myColor = Color.GRAY;
		else
			myColor = Color.WHITE;
		numFights = 3;
	}

	public Color getColor(){
		return myColor;
	}

	public int getMove(CritterInfo info){
		return Critter.NORTH;
	}

	public String toString(){
		String result = "";
		if(myColor == Color.BLACK)
			result = "B";
		else if(myColor == Color.GRAY)
			result = "G";
		else
			result = "W";
		return result;
	}

	public int fight(String opponent){
		if(numFights == 3){
			numFights = 0;
			weapon = WEAPONS[(int)(Math.random() * 3)];
		}
		numFights++;
		return weapon;
	}
}

Criteria:

class header: 1 point

instance variables private: 1 point
instance variable for color: 1 point
instance variable for weapon: 1 point
instance variable for number of fights: 1 point

constructor: 3 points, 1 point attempt, 2 point correct

getColor: 1 point
getMove: 1 point
toString: 3 points, 1 point attempt, 2 point correct
fight: 2 points, 1 point attempt, 1 point correct

Don't take off for minor syntax errors. (semicolons, braces)