Key to CSE142 Midterm, Summer 2012         

1.      Expression                             Value
        -----------------------------------------------
	3 + 5 / 2 - 10 % 6                     1
	4 + 1 + "foo" + 4 + 1                  "5foo41"
	(1 / 2 / 3.0 + (10 - 3)) / 2           3.5     
	"foo" + 2.4 / (11 % 3) + "bar"         "foo1.2bar"   
	14 % 8 % 4 - 2.0 * 3 - 3               -7.0

2. Parameter Mystery.  The program produces the following output.

	1 + 3 = 5
	5 + 10 = 3
	7 + 7 = 4
	2 + 2 = 5
	0 + 3 = 4

3.      Method Call             Output Produced
        ---------------------------------------
        ifElseMystery(0, 0);	0 0
        ifElseMystery(10, 4);	6 4
        ifElseMystery(3, 6);	4 9
        ifElseMystery(13, 8);	5 13

4.      Method Call             Output Produced
        --------------------------------------
        whileMystery(1, 2);	1 1 0
        whileMystery(2, 5);	3 4 3
        whileMystery(3, 10);	4 6 9 7

5.                 m == 1              m % 2 == 1                o <= e
            +---------------------+---------------------+---------------------+
    Point A | sometimes           | sometimes           | always              |
            +---------------------+---------------------+---------------------+
    Point B | never               | sometimes           | sometimes           |
            +---------------------+---------------------+---------------------+
    Point C | never               | never               | sometimes           |
            +---------------------+---------------------+---------------------+
    Point D | sometimes           | sometimes           | always              |
            +---------------------+---------------------+---------------------+
    Point E | always              | always              | always              |
            +---------------------+---------------------+---------------------+          

6. One possible solution appears below:
 
public static void diagnose(Scanner console) {
    System.out.print("Temperature? ");
    double temparature = console.nextDouble();
    System.out.print("Headache? ");
    String headache = console.next().toLowerCase();
    System.out.print("Heart rate? ");
    int heartRate = console.nextInt();

    if (heartRate <= 20) {
        System.out.println("Heart Problem");
    } else if (headache.startsWith("y")) {
        if (temparature >= 100.4) {
            System.out.println("Fever");
        } else {
            System.out.println("Cold");
        }
    } else {
        System.out.println("Just Fine");
    }
}        

7. Four possible solutions appear below:

public static int exp(int base, int target) {
    if (base < 2) {
        return -1;
    } else if (target < 1) {
        return -1;
    }
    int exp = 0;
    int cur = 1;
    while (cur < target) {
        exp++;
        cur = cur * base;
    }
    return exp;
}

public static int exp(int base, int target) {
    if (base < 2) {
        return -1;
    }
    if (target < 1) {
        return -1;
    }
    int exp = 0;
    int result = (int)Math.pow(base, exp);
    while (result < target) {
        exp++;
        result = (int)Math.pow(base, exp);
    }
    return exp;
}

public static int exp(int base, int target) {
    if (base < 2 || target < 1) {
        return -1;
    }
    int exp = 0;
    while (target > 1) {
        exp++;
        // I don't expect students to come up with this.
        if (target % base != 0) {
            target += base - target % base;
        }
        target = target / base;
    }
    return exp;
}

public static int exp(int base, int target) {
    if (base < 2 || target < 1) return -1;
    int result = (int)Math.ceil(Math.log10(target) / Math.log10(base));
    if (Math.pow(base, result - 1) >= target)
        result--;
    return result;
}

8. Three possible solutions appear below:      

public static int diffChars1(String a, String b) {
    if (b.length() < a.length()) {
        String temp = a;
        a = b;
        b = temp;
    }
    a = a.toLowerCase();
    b = b.toLowerCase();
    int diff = 0;
    for (int i = 0; i < a.length(); i++) {
        if (a.charAt(i) != b.charAt(i)) {
            diff++;
        }
    }
    return diff + b.length() - a.length();
}

public static int diffChars2(String a, String b) {
    int diff = 0;
    for (int i = 0; i < Math.min(a.length(), b.length()); i++) {
        if (!a.substring(i, i + 1).equalsIgnoreCase(b.substring(i, i + 1))) {
            diff++;
        }
    }
    return diff + Math.abs(a.length() - b.length());
}

public static int diffChars3(String a, String b) {
    int diff = 0;
    while (a.length() > 0 && b.length() > 0) {
        if (a.toLowerCase().charAt(0) != b.toLowerCase().charAt(0)) {
            diff++;
        }
        a = a.substring(1);
        b = b.substring(1);
    }
    return diff + a.length() + b.length();
}

public static int diffChars4(String a, String b) {
    int diff = Math.max(a.length(), b.length());
    for (int i = 0; i < Math.min(a.length(), b.length()); i++) {
        if (("" + a.charAt(i)).equalsIgnoreCase("" + b.charAt(i))) {
            diff--;
        }
    }
    return diff;
}