剑指 Offer 26. 树的子结构

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     struct TreeNode *left;
 6  *     struct TreeNode *right;
 7  * };
 8  */
 9 
10 bool isSubStructure2(struct TreeNode* A, struct TreeNode* B) {
11     if (B == NULL) 
12         return true;
13     if (A == NULL)
14         return false;
15     if (A->val != B->val)
16         return false;
17     return isSubStructure2(A->left, B->left) && isSubStructure2(A->right, B->right);
18  }
19 
20 bool isSubStructure(struct TreeNode* A, struct TreeNode* B){
21     bool result =false;
22     if (A && B) {
23         if (A->val == B->val) {
24             result = isSubStructure2(A, B);
25         }
26         if (result == false) {
27             result = isSubStructure(A->left, B);
28         }
29         if (result == false) 
30             result = isSubStructure(A->right, B);
31     }
32     return result;
33 }