Binary_tree_is_symmetirc_or_not.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool isIdentical(TreeNode *r1, TreeNode *r2)
    {
        if(!r1&&!r2)
        return true;
        if(!r1||!r2)
        return false;
        if(r1->val!=r2->val)
        return false;
        return isIdentical(r1->left,r2->right)&&isIdentical(r1->right,r2->left);
    }
    bool isSymmetric(TreeNode* root) 
    {
        if(!root)
        return true;
	    bool b=isIdentical(root->left,root->right);
	    return b;
    }
};