Question

I have created a binary search tree with {2,5,3,4,9,1,7,...,100} digits.

how can i save it as preorder?
thanks

EDIT: Consider I have { 3,7,1,2} and make a binary search tree with these digits and I want to save this tree as preorder which is {3,1,2,7}

Answer 1

Seeh here on literateprograms :

public List<E> toList() {
    List<E> result = new ArrayList<E>();
    treeToList(root, result);
    return result;
}

private void treeToList(Node<E> node, List<E> goal) {
    if (node != null) {
        treeToList(node.left, goal);
        goal.add(node.value);
        treeToList(node.right, goal);
    }
}

A complete article on binary trees and PreOrder traversals.