树的子结构

题目：
输入两棵二叉树A和B，判断B是不是A的子结构。
解答：
 1 public class Solution {
 2 
 3     public static boolean HashSubTree(TreeNode root1, TreeNode root2) {
 4         boolean result = false;
 5 
 6         if(root1 != null && root2 != null) {
 7             if(Equal(root1.val, root2.val)) {
 8                 result = DoesTree1HaveTree2(root1, root2);
 9             }
10 
11             if(!result) {
12                 result = DoesTree1HaveTree2(root1.left, root2);
13             }
14 
15             if(!result) {
16                 result = DoesTree1HaveTree2(root1.right, root2);
17             }
18         }
19 
20         return result;
21     }
22 
23     private static boolean Equal(int val1, int val2) {
24         return val1 == val2? true:false;
25     }
26 
27     private static boolean DoesTree1HaveTree2(TreeNode root1, TreeNode root2) {
28         if(root2 == null) {
29             return true;
30         }
31 
32         if(root1 == null) {
33             return false;
34         }
35 
36         if(!Equal(root1.val, root2.val)) {
37             return false;
38         }
39 
40         return DoesTree1HaveTree2(root1.left, root2.left) && DoesTree1HaveTree2(root1.right, root2.right);
41     }
42 }