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);

    }

};