在二叉树中找到一个节点的后继节点

现在有一种新的二叉树节点类型如下：

public class Node {

　　 public int value; public Node left;

　　public Node right;

　　public Node parent;

　　public Node(int data) { this.value = data;

} }

在二 叉树的中序遍历的序列中， node的下一个节点叫作node的后继节点。该结构比普通二叉树节点结构多了一个指向父节点的parent指针。假 设有一 棵Node类型的节点组成的二叉树，树中每个节点的parent指针 都正确地指向 自己的父节点，头节点的parent指向null。只给一个在 二叉树中的某个节点 node，请实现返回node的后继节点的函数。

package my_basic.class_4;

public class Code_03_SuccessorNode {
    public static class Node {
        int value;
        Node parent;
        Node left;
        Node right;
        public Node(int value) {
            super();
            this.value = value;
        }
    }
    
    public static Node getSuccessNode(Node node) {
        if (node == null) {
            return null;
        }
        if (node.right != null) {
            return getMostLeft(node.right);
        }else {
            Node parent = node.parent;
            while (parent != null && parent.left != node) {
                node = parent;
                parent = node.parent;    
            }
            return parent;
        }
    }

    private static Node  getMostLeft(Node head) {
        if (head.left!=null) {
            head = head.left;
        }
        return head;
        
    }
    
    public static void main(String[] args) {
        Node head = new Node(6);
        head.parent = null;
        head.left = new Node(3);
        head.left.parent = head;
        head.left.left = new Node(1);
        head.left.left.parent = head.left;
        head.left.left.right = new Node(2);
        head.left.left.right.parent = head.left.left;
        head.left.right = new Node(4);
        head.left.right.parent = head.left;
        head.left.right.right = new Node(5);
        head.left.right.right.parent = head.left.right;
        head.right = new Node(9);
        head.right.parent = head;
        head.right.left = new Node(8);
        head.right.left.parent = head.right;
        head.right.left.left = new Node(7);
        head.right.left.left.parent = head.right.left;
        head.right.right = new Node(10);
        head.right.right.parent = head.right;
        
        Node test = head.left.left;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.left.left.right;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.left;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.left.right;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.left.right.right;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.right.left.left;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.right.left;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.right;
        System.out.println(test.value + " next: " + getSuccessNode(test).value);
        test = head.right.right; // 10's next is null
        System.out.println(test.value + " next: " + getSuccessNode(test));
    }
}