【Leetcode】Given a binary tree, check whether it is a mirror of itself

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

/** * 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 isMirrorSame(TreeNode *treea, TreeNode *treeb)    {        if(!treea && !treeb) return true;        if((treea&&!treeb) || (treeb&&!treea)) return false;        if(treea->val != treeb->val) return false;        return isMirrorSame(treea->left,treeb->right) && isMirrorSame(treea->right,treeb->left);    }    bool isSymmetric(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!root) return true;        return isMirrorSame(root->left,root->right);    }};