Given a BST and its root, print all sequences of nodes which give rise to the same bst

Question

Given a BST, find all sequences of nodes starting from root that will essentially give the same binary search tree.

Given a bst, say

  3
 /  \\
1             


        

Answer 1

public class Solution {
    ArrayList> result;
    /*Return the children of a node */
    ArrayList getChilden(TreeNode parent) {
        ArrayList child = new ArrayList();
        if(parent.left != null) child.add(parent.left);
        if(parent.right != null) child.add(parent.right);
        return child;
    }
    /*Gets all the possible Compinations*/
    void getPermutations(ArrayList permutations, LinkedList current) {
        if(permutations.size() == 0) {
            result.add(current);
            return;
        }
        int length = permutations.size();
        for(int i = 0; i < length; i++) {
            TreeNode node = permutations.get(i);
            permutations.remove(i);
            ArrayList newPossibilities = new ArrayList();
            newPossibilities.addAll(permutations);
            newPossibilities.addAll(getChilden(node));
            LinkedList newCur = new LinkedList();
            newCur.addAll(current);
            newCur.add(node.val);
            getPermutations(newPossibilities, newCur);
            permutations.add(i,node);
        }
    }

    /*This method returns a array of arrays which will lead to a given BST*/
    ArrayList> inputSequencesForBst(TreeNode node) { 
        result = new ArrayList>();
        if(node == null)
            return result;
        ArrayList permutations = getChilden(node);
        LinkedList current = new LinkedList();
        current.add(node.val);
        getPermutations(permutations, current);
        return result;
    }
}

My solution. Works perfectly.