Java How to Program, Early 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

   $${\mathit{\text{base}}}^{\text{ exponent}}$$

   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

   $${\mathit{\text{base}}}^{\text{ exponent}}=\mathit{\text{base}}\cdot {\mathit{\text{base}}}^{\text{ exponent}-1}$$

   and the terminating condition ...