How to recursively split a string in half and then split the smaller strings in Java

Question

on my recent midterm I had a question where I was told to split a big string into 2 equal small and split the smaller strings into halves again. I know it has to be done recursively for this question but I am not aware of how to apply it to Java code.

Any help would be great, Thank you.

public class Question7a {

public static void main(String[] args) {
    String strings = "aaaa bbbb cccc dddd";
    Question7a question7a = new Question7a();
    question7a.splitString(strings);
}

public void splitString(String words){
        int m = words.length() / 2; //gets the middle length of the string to split there.
        for (int i=0; i < m; i++) {
        String[] halves = {words.substring(0, m), words.substring(m)};
        System.out.println(halves[0]); //first half of the string
        System.out.println(halves[1]); //second part
            if(halves[0].equals(true)){
                int m2 = halves.length/2; //Intent was to get the middle of the new half.
                halves[0] = {hal.substring(0, m2), words.substring(m2)};
                halves[1] = {words.substring(0, m2), words.substring(m2)};
                System.out.println(halves[0]);
                System.out.println(halves[1]);
            }
            else{
                System.out.println("Null");
    }
}

}

Kind of want a output to something like:

"aaaa bbbb"      cccc  dddd
   |                |
   |                |
"aaaa" "bbbb"    cccc  dddd
   |      |
   |      |  
"aa" "aa" "bb" "bb"

and similar (not sure if this is the right way to look at it) for the other half.

Answer 1

Try this:

import java.util.Stack;
class Hackerearth{
    public static void main(String args[] ) throws Exception {
        Stack<String> st = new Stack<>();
        String str = "aaaa bbbb cccc dddd";
        st.push(str);
        split(st);
    }

    public static void split(Stack<String> st){
        while(!st.empty()){
            String s = st.pop();
            if(s.length() == 1){
                System.out.println(s);
            }
            else{
                int mid = s.length() / 2;
                String first = s.substring(0, mid);
                String second = s.substring(mid, s.length());
                st.push(second);
                st.push(first);
            }
        }
    }
}

You can use Stack in Java.util package.. It has push and pop methods predefined to add and remove items.. Stack Documentation