Nested indented output with a recursion method

Question

I have an assignment to use a recursive method to print out multiple lines, each line having 3 more spaces in front of it than the previous. Here is a picture of the desired output (https://i.sstatic.net/kKz9z.png).

This is the code I have so far:

public class Prog6d {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int input = scan.nextInt();
        System.out.println(printFactorial(input));
    }

    //Calculates the factorial
    public static int printFactorial(int input) {
        if (input == 1) {
            return 1;
        }
        System.out.println("factorial(" + input + ")");
        System.out.print("   ");
        return input*printFactorial(input-1);
    }
}

I know how to make the spaces appear correctly using a for-loop, but I have no idea how to do this with recursion.

Prune · Accepted Answer · 2017-04-06 00:32:06Z

4

I do this often. I have two basic methods, related:

Make a global string variable indent, initialized to the empty string. On entry to the function, lengthen it by three spaces. When you leave, shorten it to the previous length.
Add a parameter indent. The initial call is with an empty string; each recursion concatenates three spaces to the value.

In each case, I just use indent as the first thing printed on the line.

Does that solve your problem?

answered Apr 6, 2017 at 0:32

Prune

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1 Comment

Davislor Over a year ago

I would recommend approach number two over approach number one, because you’ll save yourself a lot of headache debugging your programs if you avoid global variables. If you make your calls tail-recursive, the parameterized version should be equally efficient.

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