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  1. #1
    zlwilly is offline Member
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    Default Recursive Counting

    I have an an exercise for class that I have been working on, trying to teach us recursion. I am able to nearly wrap my head around the subject, but have one small problem left. The program is supposed to take a large integer and a single digit integer, and tell how many times the small int occurs in the large one. This much I can get it to do.

    However, it does the counting using a "static int i" that can be accessed by any part of the program, and I would prefer to use the recursion itself to accomplish this.

    Here's the code.

    Java Code:
    import java.util.*;
    public class testCopy
    {
    static int i=0;
        public static void main (String args[])
        {
            
            int integer=0;
            int digit=0;
            Scanner keyboard = new Scanner (System.in);
            System.out.println("Please enter an integer:");
            integer=keyboard.nextInt();
            System.out.println("Please enter a single digit:");
            digit=keyboard.nextInt();
            System.out.println();
            System.out.println("You have chosen integer "+integer+" and digit "+digit+".");
            System.out.println();
            System.out.println(frequencyCount(integer,digit));
        }
        
        public static int frequencyCount(int n,int d)
        {
              
            if ((n==0) && (Integer.toString(n).length())==1)
            return(i);
            
            else if(n%10==d)
              {
                i++;
            return (frequencyCount(n/10,d) ); //if whatever is equal to d then return whats left plus one more
              } 
            else 
            return (frequencyCount(n/10,d));
        }
        
    }
    Is there some way to use the recursion to do the counting for me?
    Any help would be greatly appreciated! Thanks!

  2. #2
    emceenugget is offline Senior Member
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    Default

    looks like you just need to get used to recursion. trying to make help as obscure as possible, here's some simple straightforward pseudocode to think on:

    Java Code:
    if current digit matches
    then return recursive call + 1
    else return recursive call

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