Java Recursion return boolean

Question

Given an array of integers f, I want to see if f[k]=k for some k in the array. I'm having some trouble because I would like to return on the left and right half of the array, but I am not sure how to go about doing that. This is what I have so far:

public class Find {

    int a = 0;

    public boolean find(int[] f) {
        if(f.length < 1) {
            return false;
        }
        System.out.println(f[0] + " " + a);
        if(f.length == 1 && f[0] == a) {
            return true;
        }
        if(f.length == 1 && f[0] != a) {
            return false;
        }

        int[] L = Arrays.copyOfRange(f, 0, f.length / 2);
        int[] R = Arrays.copyOfRange(f, f.length / 2, f.length);
        find(L);
        a++;
        //find(R);

        return find(R); //only finds in the right half...
    }


    public static void main(String[] args) {
        Find F = new Find();
        int[] test = {0, 13, 2, 3, 4};
        System.out.println(F.find(test));
    }
}

I'm worried that you're not passing in what it is that you're searching to the method, but rather keeping it as a field. It'll work like that (assuming one's code is correct), but you'll have to reassign a every time on the object instead of changing your method call. — Makoto
– Makoto, Commented May 11, 2014 at 2:28
@Makoto: Could you elaborate? I don't quite understand what you are getting at. — Student
– Student, Commented May 11, 2014 at 2:30
Sure. Instead of having a as a field, add it as a parameter to your method instead, so your signature to find would be public boolean find(int[] data, int value). This way, you could just call the method with whichever value you wanted (e.g. find(test, 2)). Actually, the way it's written now, it'll always be finding 0 - that may not be correct depending on your test data. You're definitely going to want to fix that. — Makoto
– Makoto, Commented May 11, 2014 at 2:32

Drakosha · Accepted Answer · 2014-05-11 02:29:23Z

1

You could do the following, you currently search the left side but do not return the result:

return find(R) || find(L);

answered May 11, 2014 at 2:29

Drakosha

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