【剑指offer】十一。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      boolean res = false ;
17      if(root1!=null&&root2!=null){
18          if(root1.val==root2.val){
19              res = doesHas(root1,root2);
20          }
21          if(!res){
22              res = HasSubtree(root1.left,root2) ;
23          }
24          if(!res){
25              res = HasSubtree(root1.right,root2) ;
26          }
27      }
28      return res ;
29     }
30     private boolean doesHas(TreeNode root1, TreeNode root2) {
31     if(root2==null){
32         return true ;
33     }
34     if(root1==null){
35         return false ;
36     }
37     if(root1.val!=root2.val){
38         return false ;
39     }
40       
41     return doesHas(root1.left,root2.left)&&doesHas(root1.right,root2.right);
42 }
43 }