剑指Offer之二叉树的镜像

题目描述

操作给定的二叉树，将其变换为源二叉树的镜像。

输入描述:

二叉树的镜像定义：源二叉树 
    	    8
    	   /  \
    	  6   10
    	 / \  / \
    	5  7 9 11
    	镜像二叉树
    	    8
    	   /  \
    	  10   6
    	 / \  / \
    	11 9 7  5

解题思路：递归遍历二叉树，如果节点不为空，则交换节点的左右孩子。然后重复上述步骤

public class 二叉树的镜像 {
    public static void Mirror(TreeNode root) {
        //这样的情况,为空如何处理
        if (root == null){
            System.out.println("输入为空。。。");
        }
        TreeNode my = switchNode(root);
        System.out.println(my.val);
    }
    public static TreeNode switchNode(TreeNode treeNode){
        if (treeNode == null){
            return treeNode;
        }
        //交换左右孩子
        TreeNode left = treeNode.left;
        TreeNode right = treeNode.right;
        treeNode.right = left;
        treeNode.left = right;
        //交换孩子节点的左右孩子
        switchNode(treeNode.right);
        switchNode(treeNode.left);
        return treeNode;
    }

    public static void main(String [] args){
        TreeNode treeNode1_1 = new TreeNode(8);
        TreeNode treeNode1_2 = new TreeNode(6);
        TreeNode treeNode1_3 = new TreeNode(10);
        TreeNode treeNode1_4 = new TreeNode(5);
        TreeNode treeNode1_5 = new TreeNode(7);
        TreeNode treeNode1_6 = new TreeNode(9);
        TreeNode treeNode1_7 = new TreeNode(11);
        treeNode1_1.left = treeNode1_2;
        treeNode1_1.right = treeNode1_3;
        treeNode1_2.left = treeNode1_4;
        treeNode1_2.right = treeNode1_5;
        treeNode1_3.left = treeNode1_6;
        treeNode1_3.right = treeNode1_7;
        Mirror(treeNode1_1);
    }
}

坚持写，总会提高！