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Key to CSE142 Midterm, Autumn 2013 handout #15
1. Expression Value
-----------------------------------------------
13 + 2 * 5 / 3 16
2.5 * 2 * 5 / 10 + 1.5 4.0
85 % 10 + 4 % 10 - 17 % 3 7
2 + 3 + "." + (3 + 4) + 2 * 3 "5.76"
482 / 10 / 5 / 2.0 * 2 + 14 / 5 11.0
2. Parameter Mystery. The program produces the following output.
skip likes to drive with george
george likes to work with drive
george likes to skip with mary
john likes to dance with mary
3. Method Call Output Produced
---------------------------------------
ifElseMystery(14, 14); 14 13
ifElseMystery(4, 5); 7 5
ifElseMystery(10, 5); 12 10
ifElseMystery(2, 8); 3 8
4. Method Call Output Produced
---------------------------------------
mystery(8); 1 8
mystery(32); 2 5
mystery(184); 3 13
mystery(8239); 4 22
5. next == 0 prev == 0 next == prev
+---------------------+---------------------+---------------------+
Point A | sometimes | always | sometimes |
+---------------------+---------------------+---------------------+
Point B | never | sometimes | sometimes |
+---------------------+---------------------+---------------------+
Point C | never | never | always |
+---------------------+---------------------+---------------------+
Point D | sometimes | never | sometimes |
+---------------------+---------------------+---------------------+
Point E | always | sometimes | sometimes |
+---------------------+---------------------+---------------------+
6. One possible solution appears below.
public static void giveProblems(Scanner console, int numProblems) {
Random r = new Random();
int numRight = 0;
for (int i = 1; i <= numProblems; i++) {
int x = r.nextInt(12) + 1;
int y = r.nextInt(12) + 1;
System.out.print(x + " * " + y + " =? ");
int answer = x * y;
int response = console.nextInt();
if (response == answer) {
System.out.println("correct");
numRight++;
} else {
System.out.println("incorrect...the answer was " + answer);
}
}
System.out.println(numRight + " of " + numProblems + " correct");
}
7. One possible solution appears below.
public static int printSequenceTo(double value) {
double sum = 0.5;
System.out.print("1/2");
int n = 1;
while (sum < value) {
n++;
System.out.print(" + " + n + "/" + (n + 1));
sum = sum + (double) n / (n + 1);
}
System.out.println(" = " + sum);
return n;
}
8. One possible solution appears below.
public static int weave(int x, int y) {
int result = 0;
int multiplier = 1;
while (x != 0 || y != 0) {
result = result + multiplier * (x % 10 * 10 + y % 10);
multiplier = multiplier * 100;
x = x / 10;
y = y / 10;
}
return result;
}
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Stuart Reges
Last modified: Fri Sep 16 16:16:07 PDT 2011