剑指offer——树的子结构

 1 /**
 2 public class TreeNode {
 3     int val = 0;
 4     TreeNode left = null;
 5     TreeNode right = null;
 6  
 7     public TreeNode(int val) {
 8         this.val = val;
 9  
10     }
11  
12 }
13 */
14 public class Solution {
15     public boolean HasSubtree(TreeNode root1,TreeNode root2){
16         if(root1==null || root2==null){
17             return false;
18         }
19         boolean result=false;
20         if(root1!=null && root2!=null){
21             if(root1.val==root2.val){
22                 result=doesTree1HaveTree2(root1,root2);
23             }
24             if(!result){
25                 result=HasSubtree(root1.left,root2);
26             }
27             if(!result){
28                 result=HasSubtree(root1.right,root2);
29             }
30              
31         }
32         return result;
33     }
34     public boolean doesTree1HaveTree2(TreeNode root1,TreeNode root2){
35         if(root2==null){
36             return true;
37         }
38         if(root1==null){
39             return false;
40         }
41         if(root1.val!=root2.val){
42             return false;
43         }
44         return doesTree1HaveTree2(root1.left,root2.left) && doesTree1HaveTree2(root1.right,root2.right);
45     }   
46 }