Before you keep reading...

Runestone Academy can only continue if we get support from individuals like you. As a student you are well aware of the high cost of textbooks. Our mission is to provide great books to you for free, but we ask that you consider a $10 donation, more if you can or less if $10 is a burden.

Support Runestone Academy Today

11.6. Code Practice for Recursion

Replace the “ADD CODE HERE” below with the code to complete the findSum method. The method should take the sum of every value that is less than or equal to n. For example, findSum(3) should return 6. The output of the program should be 15.

public class Recursion { public static int findSum(int n) { // write code here } public static void main(String[] args) { System.out.println(findSum(5)); } }

In order to find the sum of all the numbers that are less than or equal to n, we can use recursion. When findSum(5) is called, since 5 is not equal to 0, the program will go to the else statement. The method will then return 5 + findsum(4). findSum(4) will return 4 + findSum(3), findSum(3) will return 3 + findSum(2), findSum(2) will return findSum(1), findSum(1) will return 1 + findSum(0). findSum(0) will return 0. Therefore, findSum(5) will be 5+4+3+2+1+0, which is euqal to 15.

public class Recursion { public static int findSum(int n) { if (n == 0) return 0; else return n + findSum(n - 1); } public static void main(String[] args) { System.out.println(findSum(5)); } }

Before you keep reading...

Making great stuff takes time and $$. If you appreciate the book you are reading now and want to keep quality materials free for other students please consider a donation to Runestone Academy. We ask that you consider a $10 donation, but if you can give more thats great, if $10 is too much for your budget we would be happy with whatever you can afford as a show of support.

Support Runestone Academy Today

Show Comments

If you would like to try writing recursive methods check out the recursion problems at CodingBat at http://codingbat.com/java/Recursion-1.

You have attempted 1 of 3 activities on this page