101. Symmetric Tree.cpp

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

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

    1
   / \
  2   2
 / \ / \
3  4 4  3
But the following [1,2,2,null,3,null,3] is not:
    1
   / \
  2   2
   \   \
   3    3
Note:
Bonus points if you could solve it both recursively and iteratively.
*/

/**
 * 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 isSymmetric(TreeNode* root) {
        return root?isSame(root->left,root->right):true;
    }
    
    bool isSame(TreeNode* lTree,TreeNode* rTree)
    {     
        if(!lTree || !rTree)
        {
            return lTree==rTree;
        }
        return (lTree->val==rTree->val) && isSame(lTree->left,rTree->right) && isSame(lTree->right,rTree->left);
    }
};