100. Same Tree

Well, very straightforward DFS solution.

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 == NULL && q== NULL) return true;  
14:      if (p == NULL && q != NULL || p != NULL && q == NULL || p->val != q->val) return false;  
15:      return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);  
16:    }  
17:  };