Computer Science 210

Data Structures

Fall 2019, Siena College

Sum1ToNRec BlueJ Project

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Sum1ToNRec Source Code

The Java source code for Sum1ToNRec is below. Click on a file name to download it.

/** * Example Sum1ToNRec: computing a sum with a simple recursive method * * @author Jim Teresco, The College of Saint Rose, CSC 523, Summer 2014 * @version Fall 2019 * */ public class Sum1ToNRec { /** a recursive version of the sumNumbersTo method computes 1 + 2 + ... + limit @param limit the upper limit of the range of numbers to sum @return the sum of the numbers from 1 to limit */ public static int sumNumbersTo(int limit) { // first, we check for the base case if (limit == 1) return 1; // otherwise, we have to make a recursive method call to compute the // sum of the first limit-1 numbers, then add in limit to get our answer return sumNumbersTo(limit - 1) + limit; } /** main method to test our method @param args not used. */ public static void main(String[] args) { // for this example, we will just print out a few of these sums int firstSum = sumNumbersTo(10); System.out.println("The sum of the numbers 1-10 is " + firstSum); int secondSum = sumNumbersTo(82); System.out.println("The sum of the numbers 1-82 is " + secondSum); // we skip this case, since it leads to an error: a stack overflow! // more on this later. //int thirdSum = sumNumbersTo(96352); //System.out.println("The sum of the numbers 1-96352 is " + thirdSum); // or we can use this within a loop for (int number = 1; number <= 9; number++) { // and we can use the value as part of a printout or any other expression // if we do not want or need to save it in a variable System.out.println("The sum of the numbers 1-" + number + " is " + sumNumbersTo(number)); } } }