重建二叉树

给定一棵二叉树，假设每个节点都用唯一的字符来表示。
假设已经有了前序遍历和中序遍历的结果，希望通过一个算法重建这棵树。
前序遍历结果：a b d c e f
中序遍历结果：d b a e c f

/*
 * 根据前序和中序遍历重建二叉树，并输出后序遍历
 */
public class RebuildBinaryTree {

    public static void main(String[] args) {
        char[] preOrder = { 'a', 'b', 'd', 'c', 'e', 'f' };
        char[] inOrder = { 'd', 'b', 'a', 'e', 'c', 'f' };
        RebuildBinaryTree rebulid = new RebuildBinaryTree();
        Node root = rebulid.rebuildBinaryTree(preOrder, 0, preOrder.length - 1, inOrder, 0, inOrder.length - 1);
        rebulid.postOrder(root);
    }

    private Node rebuildBinaryTree(char[] pre, int begin1, int end1, char[] in, int begin2, int end2) {
        if (begin1 > end1 || begin2 > end2)
            return null;
        char rootData = pre[begin1];
        Node head = new Node(rootData);
        int divider = findIndexInArray(in, rootData, begin2, end2);
        int offset = divider - begin2 - 1;
        head.left = rebuildBinaryTree(pre, begin1 + 1, begin1 + 1 + offset, in, begin2, begin2 + offset);
        head.right = rebuildBinaryTree(pre, begin1 + 2 + offset, end1, in, divider + 1, end2);
        return head;
    }

    private int findIndexInArray(char[] a, char x, int begin, int end) {
        for (int i = begin; i <= end; i++) {
            if (a[i] == x)
                return i;
        }
        return -1;
    }

    private void postOrder(Node root) {
        if (root.left != null) {
            postOrder(root.left);
        }
        if (root.right != null) {
            postOrder(root.right);
        }
        System.out.print(root.value);
    }

    class Node {

        char value;
        Node left;
        Node right;

        public Node(char value) {
            this.value = value;
        }

        public int getValue() {
            return value;
        }

        public void setValue(char value) {
            this.value = value;
        }

        public Node getLeft() {
            return left;
        }

        public void setLeft(Node left) {
            this.left = left;
        }

        public Node getRight() {
            return right;
        }

        public void setRight(Node right) {
            this.right = right;
        }

    }

}