100. 相同的树

 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 isSameTree(TreeNode* p, TreeNode* q) {
13       if(p == nullptr && q== nullptr) return true;
14       if(p == nullptr || q == nullptr) return false;
15       if(p->val != q->val) return false;
16       return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
17     }
18 };