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 null;
        TreeNode t = new TreeNode(pRoot.val);
        mirrorReady(t, pRoot);
        return t;
    }
    public void mirrorReady (TreeNode t1, TreeNode t2) {
        if (t1.right != null && t2.left != null) {
            mirrorReady(t1.right, t2.left);
        } else if (t1.right == null && t2.left != null) {
            t1.right = new TreeNode(t2.left.val);
            mirrorReady(t1.right, t2.left);
        }

        if (t1.left != null && t2.right != null) {
            mirrorReady(t1.left, t2.right);
        } else if (t1.left == null && t2.right != null) {
            t1.left = new TreeNode(t2.right.val);
            mirrorReady(t1.left, t2.right);
        }
    }
}