C Sc 227: 20 Recursion Questions for Quiz 5 on 12-July-2007 @ 10:30am
1. Write the return values from each call to the method named mystery. (4pts)
____mystery(0) ___mystery(1) ____mystery(2) ____mystery(3)
public int mystery(int n) {
if (n <= 0)
return 1;
else
return 3 + mystery(n - 1);
}
2. Write the return values from each call to the method named mysteryTwo. (6pts)
______ mysteryTwo("T") ________ mysteryTwo("ab") ________ mysteryTwo("123")
public String mysteryTwo(String s) {
if (s.length() == 0)
return "";
else
return s.charAt(0) + "/" + mysteryTwo(s.substring(1)) ;
}
3. Write the output generated by the following method calls (6pts)
mystery("X", 1);
mystery("Y", 2); mystery("Z", 6);
public void mystery(String s, int digit) {
if(digit <= 1)
System.out.println(digit);
else {
s = s + "<";
mystery(s, digit - 2);
System.out.println(s + digit);
}
}
4. Write the output of stars with arguments 1, 2, and 3
stars(1)
stars(2)
stars(3)
public void stars(int n) {
if (n > 1)
stars(n-1);
for (int i = 0; i < n; i++)
System.out.print("*");
System.out.println();
}
1
