Java How To Program, Late Objects, 11th Edition

Exercises

1. 18.7 What does the following code do?

   
   1     public int mystery(int a, int b) {
   2        if (b == 1) {
   3           return a;
   4         }
   5        else {
   6           return a + mystery(a, b - 1);
   7         }
   8     }
   
   

2. 18.8 Find the error(s) in the following recursive method, and explain how to correct it (them). This method should find the sum of the values from 0 to n.

   
   1     public int sum(int n) {
   2        if (n == 0) {
   3           return 0;
   4         }
   5        else {
   6           return n + sum(n);
   7         }
   8     }
   
   

3. 18.9 (Recursive power Method) Write a recursive method power(base, exponent) that, when called, returns

   • base^exponent

   For example, power(3,4) = 3 * 3 * 3 * 3. Assume that exponent is an integer greater than or equal to 1. Hint: The recursion step should use the relationship

   • base^exponent = base · base^{exponent – 1}