剑指offer 树的子结构

 1 /*
 2 struct TreeNode {
 3     int val;
 4     struct TreeNode *left;
 5     struct TreeNode *right;
 6     TreeNode(int x) :
 7             val(x), left(NULL), right(NULL) {
 8     }
 9 };*/
10 class Solution {
11     bool IsSubtree(TreeNode* pRoot1, TreeNode* pRoot2)
12     {
13         if(pRoot2 == NULL) return true;
14         if(pRoot1 == NULL) return false;
15         if(pRoot1->val == pRoot2->val){
16             return IsSubtree( pRoot1->right, pRoot2->right ) 
17                 && IsSubtree( pRoot1->left, pRoot2->left );
18         }else return false;
19     }
20 public:
21     bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2)
22     {
23         if( pRoot1 == NULL || pRoot2 == NULL) 
24             return false;
25         return IsSubtree(pRoot1,pRoot2) || 
26             HasSubtree(pRoot1->left,pRoot2) || 
27             HasSubtree(pRoot1->right,pRoot2);
28     }
29 };