摘要：
import java.util.LinkedList;import java.util.Queue;public class judgeTree { public static boolean judge(TreeNode root){ if(root == null) return true; 阅读全文
摘要：
public class TreeNode { TreeNode right; TreeNode left; int val;} import java.util.Stack;public class PreOrder { /* * 递归 */ public void preorder(TreeNo 阅读全文