using System;
using System.Collections.Generic;

/*
public class TreeNode
{
	public int val;
	public TreeNode left;
	public TreeNode right;

	public TreeNode (int x)
	{
		val = x;
	}
}
*/

class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
     *
     * 
     * @param pRoot TreeNode类 
     * @return TreeNode类
     */
    public TreeNode Mirror (TreeNode pRoot) {
        if(pRoot == null) return pRoot;
        TreeNode node = pRoot.left;
        pRoot.left = pRoot.right;
        pRoot.right = node;
        if(pRoot.left != null) Mirror(pRoot.left);
        if(pRoot.right != null) Mirror(pRoot.right);
        return pRoot;
    }
}