原题：
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 .递归遍历一下就好。
代码如下：
/** * Definition for a binary tree node. * struct TreeNode { * int val; * struct TreeNode *left; * struct TreeNode *right; * }; */ bool isSubtree(struct TreeNode* s, struct TreeNode* t) { bool isSame(struct TreeNode* ,struct TreeNode*); if(s==NULL) return false; if(isSame(s,t)) return true; //s.left-tree和t-tree是不是相等树？ //s.right-tree和t-tree是不是相等树？ return isSubtree(s->left,t) || isSubtree(s->right,t); //判断s-tree和t-tree是不是相等树 } bool isSame(struct TreeNode* s,struct TreeNode* t) { if (s == NULL && t == NULL) return true; if (s == NULL || t == NULL) return false; return s->val == t->val &&isSame(s->left, t->left) &&isSame(s->right, t->right); }
