数据结构与算法(JAVA版)7_6:返回中序遍历后的二叉树中，某一结点的后继结点

定义一个二叉树
class Node{
V value;
Node left;
Node right;
Node parent;
}
给你二叉树中的某个结点，返回该节点的后继结点（后继结点是指：将二叉树中序遍历后，一个结点的下一个结点就是该结点的后继结点）

package com.inspire.chapter7;

public class Code07_SuccessorNode {

	public static class Node {
		public int value;
		public Node left;
		public Node right;
		public Node parent;

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

	public static Node getSuccessorNode(Node node) {
		if (node == null) {
			return null;
		}
		if (node.right != null) {// 如果该结点有右子树，则返回右子树的最左结点
			return getLeftMost(node.right);
		} else {// 如果没有右子树
			Node parent = node.parent;
			while (parent != null && parent.left != node) {// 当前节点是其父亲节点右孩子（画一下就知道了）
				node = parent;
				parent = node.parent;
			}
			return parent;
		}
	}

	private static Node getLeftMost(Node node) {
		if (node == null) {
			return null;
		}
		while (node.left != null) {
			node = node.left;
		}
		return node;
	}

	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: " + getSuccessorNode(test).value);
		test = head.left.left.right;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.left;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.left.right;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.left.right.right;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.right.left.left;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.right.left;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.right;
		System.out.println(test.value + " next: " + getSuccessorNode(test).value);
		test = head.right.right; // 10's next is null
		System.out.println(test.value + " next: " + getSuccessorNode(test));

	}

}