[LeetCode]100. Same Tree--判断二叉树是否相同

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

分析：

/**
* 递归版本
*/
/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isSameTree(TreeNode* p, TreeNode* q) {
if(p == NULL && q == NULL)
return true;
else if(p == NULL || q == NULL)
return false;
else if(p->val != q->val)
return false;
else
return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
}
};