leetcode[101]Symmetric Tree

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree is symmetric:

    1
   / \
  2   2
 / \ / \
3  4 4  3

 

But the following is not:

    1
   / \
  2   2
   \   \
   3    3

 

Note:
Bonus points if you could solve it both recursively and iteratively.

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
bool isSame(TreeNode *p, TreeNode *q)
{
    if(p==NULL&&q==NULL)return true;
    if(p!=NULL&&q==NULL)return false;
    if(p==NULL&&q!=NULL)return false;
    return (p->val==q->val)&&isSame(p->left,q->right)&&isSame(p->right,q->left);
}
    bool isSymmetric(TreeNode *root) {
        if(root==NULL)return true;
        return isSame(root->left,root->right);
    }
};