Find all the combination of substrings that add up to the given string

Question

I\'m trying to create a data structure that holds all the possible substring combinations that add up to the original string. For example, if the string is \"java\"

Answer 1

A different recursive solution that just adds to the list results

static List> substrings(String input) {
    List> result = new ArrayList<>();
    if (input.length() == 1) {
        result.add(Arrays.asList(new String[]{input}));
    }
    else {
        //iterate j, ja, jav, jav
        for (int i = 0; i < input.length()-1; i++ ) {
            String root = input.substring(0,i+1);
            String leaf = input.substring(i+1);
            for( List strings: substrings(leaf) ) {
                ArrayList current = new ArrayList();
                current.add(root);
                current.addAll(strings);
                result.add(current);
            }
        }
        //adds the whole string as one of the leaves (ie. java, ava, va, a)
        result.add(Arrays.asList(new String[]{input}));
    }
    return result;
}