572. Subtree of Another Tree

Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.

Example 1:
Given tree s:

     3
    / \
   4   5
  / \
 1   2

Given tree t:

   4 
  / \
 1   2

Return true, because t has the same structure and node values with a subtree of s.

 

Example 2:
Given tree s:

     3
    / \
   4   5
  / \
 1   2
    /
   0

Given tree t:

   4
  / \
 1   2

Return false.

 

判断树s是否包含树t

 

C++（29ms）：

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isSubtree(TreeNode* s, TreeNode* t) {
13         if (s == NULL)
14             return false ;
15         if (isSame(s,t))
16             return true ;
17         return isSubtree(s->left , t) || isSubtree(s->right , t) ;
18     }
19     
20     bool isSame(TreeNode* s, TreeNode* t){
21         if (s == NULL && t == NULL)
22             return true ;
23         if (s == NULL || t == NULL)
24             return false ;
25         if (s->val != t->val)
26             return false ;
27         return isSame(s->left , t->left) && isSame(s->right , t->right) ;
28     }
29 };

 

posted @ 2018-03-16 14:33  __Meng  阅读(162)  评论(0)  编辑  收藏  举报