CompSci 1, Spring 2006, Java Practice Problems

1. The following subroutine returns the sum of the numbers between two integers (inclusive). public int SumBetween(int begin, int end) { int sum = 0; int k = begin; while (k <= end) { sum = sum + k; k = k + 1; } return sum; } Write the necessary code to declare an integer variable c and assign to it the sum of the numbers between 10 and 20 by calling SumBetween. (2 points)

2. Write a subroutine called SumUp that returns the sum up to an integer. As an example, the following code calls SumUp. int c; c = SumUp(5); The value in c would be 15 (1 + 2 + 3 + 4 + 5). Write SumUp below. You can, of course, use SumBetween. (3 points)

3. Write a method numDistinct that takes three integers as parameters and that returns the number of distinct integers among the three.

   For example, if the following call is made: numDistinct(18, 3, 4) the method should return 3 because the parameters represent 3 different numbers (the values 18, 3 and 4).

   By contrast, the following call: numDistinct(6, 6, 6) would return 1 because there is only 1 distinct number among the three parameters (the value 6). The values passed to your method might appear in any order whatsoever, so you cannot assume that duplicate values would appear together.

   For example, if the following call is made: numDistinct(7, 31, 7) the method should return 2 because there are 2 distinct numbers among the parameters (the values 7 and 31).

   Write your solution to numDistinct below. (5 points)