题解 | #二叉树的镜像#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public 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 null;
        }
        TreeNode treeNode = pRoot;
        TreeNode left = treeNode.left;
        treeNode.left = treeNode.right;
        treeNode.right = left;

        Mirror(treeNode.left);
        Mirror(treeNode.right);
        return pRoot;
    }
}