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) {
        // write code here
        if (pRoot == null)
            return pRoot;
        mirror(pRoot);
        return pRoot;
    }

    public void mirror(TreeNode root) {
        if (root.left == null && root.right == null)
            return;
        if (root.left != null)
            mirror(root.left);
        if (root.right != null)
            mirror(root.right);
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;

    }
}