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CSE 143

Quiz Answers

Week 6

  1. Recursive Tracing

    Method Call Output Produced
    mystery(3); 3
    mystery(42); 242
    mystery(293); 39293
    mystery(402); 20402
    mystery(2468); 8642468

  2. Recursive Programming

    One possible answer is shown below.

    public static boolean isPalindrome(String str) {
	if (str.length() <= 1) {
		return true;
	} else {
		return str.charAt(0) == str.charAt(str.length() - 1) && 
				isPalindrome(str.substring(1, str.length() - 1));
	}
}

  3. Inheritance

    Statement Output
    var2.method1(); compiler error
    var3.method1(); Rasp 1
    var1.method2(); Marion 2
    var2.method2(); Rasp 2/Marion 2
    var3.method2(); Rasp 2/Marion 2
    var4.method2(); Salmon 2/Rasp 1
    var5.method2(); compiler error
    var1.method3(); Marion 2/Marion 3
    var2.method3(); Rasp 2/Marion 2/Marion 3
    var3.method3(); Rasp 2/Marion 2/Marion 3
    var4.method3(); Salmon 2/Rasp 1/Marion 3
    var5.method3(); compiler error
    ((Salmon)var4).method2(); Salmon 2/Rasp 1
    ((Object)var3).method3(); compiler error
    ((Salmon)var2).method2(); runtime error
    ((Rasp)var5).method3(); runtime error
    ((Marion)var3).method2(); Rasp 2/Marion 2
    ((Huckle)var5).method1(); Huckle 1
    ((Salmon)var6).method1(); Rasp 1
    ((Marion)var5).method1(); compiler error