Cse 142 Midterm Key

Sample Midterm Exam #1 Key

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1. Expressions

Expression 3 * 4 + 5 * 6 + 7 * -2 1.5 * 2.0 + (5.5 / 2) + 5 / 4 23 % 5 + 31 / 4 % 3 - 17 % (16 % 10) "1" + 2 + 3 + "4" + 5 * 6 + "7" + (8 + 9) 345 / 10 / 3 * 55 / 5 / 6 + 10 / (5 / 2.0) 1 / 2 > 0 || 4 == 9 % 5 || 1 + 1 < 1 - 1

Value 28 6.75 -1 "123430717" 24.0 true

2. Parameter Mystery

tyler and tv like java

java and tyler like tv

tv and donnie like rugby

hamburger and x like tyler

tyler and java like tyler

3. If/Else Simulation

Method Call	Value Returned
mystery(4, 2) mystery(5, 4) mystery(5, 13) mystery(5, 17) mystery(4, 8)	4 5 15 20 8

4. While Loop Simulation

Method Call	Output
mystery(5, 0); mystery(3, 2); mystery(16, 5); mystery(80, 9); mystery(1600, 40);	5 1 0 1 3 2 1 0 1 8 4 2 1 2 0 2 40 19 2 9 0 4 0

5. Assertions

	y > x	z < 0	z > 0
Point A	SOMETIMES	NEVER	NEVER
Point B	NEVER	NEVER	SOMETIMES
Point C	SOMETIMES	NEVER	ALWAYS
Point D	ALWAYS	NEVER	SOMETIMES
Point E	ALWAYS	SOMETIMES	SOMETIMES

6. Programming (five solutions shown)

public static boolean hasMidpoint(int a, int b, int c) {

double mid = (a + b + c) / 3.0;

if (a == mid || b == mid || c == mid) {

return true;

} else {

return false;

}

}

public static boolean hasMidpoint(int a, int b, int c) {

double mid = (a + b + c) / 3.0;

return (a == mid || b == mid || c == mid);

}
public static boolean hasMidpoint(int a, int b, int c) {

return (a == (b + c) / 2.0 || b == (a + c) / 2.0 || c == (a + b) / 2.0);

}
public static boolean hasMidpoint(int a, int b, int c) {

int max = Math.max(a, Math.max(b, c));

int min = Math.min(a, Math.min(b, c));

double mid = (max + min) / 2.0;
return (a == mid || b == mid || c == mid);

}
public static boolean hasMidpoint(int a, int b, int c) {

return (a - b == b - c || b - a == a - c || a - c == c - b);

}

7. Programming (one solution shown)

public static void sequenceSum(double limit) {

if (limit >= 1) {

System.out.print("1");

int denomenator = 1;

double sum = 1.0;

while (sum < limit) {

denomenator++;

sum += 1.0 / denomenator;

System.out.print(" + 1/" + denomenator);

}

System.out.printf(" = %.3f\n", sum);

}

}
8. Programming (three solutions shown)

public static void favoriteLetter(Scanner console, String letter) {

System.out.println("Looking for two \"" + letter + "\" words in a row.");

int count = 0;

String word = "";

while (count < 2) {

System.out.print("Type a word: ");

word = console.next();

if (word.startsWith(letter)) {

count++;

} else {

count = 0;

}

}

System.out.println("\"" + letter + "\" is for \"" + word + "\"");

}
// uses two Strings instead of count, and uses forever/break loop

public static void favoriteLetter(Scanner console, String letter) {

System.out.println("Looking for two \"" + letter + "\" words in a row.");

System.out.print("Type a word: ");

String word1 = console.next();

System.out.print("Type a word: ");

String word2 = console.next();

while (!(word1.startsWith(letter) && word2.startsWith(letter))) {

word1 = word2;

System.out.print("Type a word: ");

word2 = console.next();

}

System.out.println("\"" + letter + "\" is for \"" + word2 + "\"");

}
// uses do/while loop

public static void favoriteLetter(Scanner console, String letter) {

System.out.println("Looking for two \"" + letter + "\" words in a row.");

int count = 0;

String word;

do {

System.out.print("Type a word: ");

word = console.next();

if (word.startsWith(letter)) {

count++;

} else {

count = 0;

}

} while (count < 2);

System.out.println("\"" + letter + "\" is for \"" + word + "\"");

}

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