LeetCode---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:

/
2 2 / \ /
3 4 4 3 But the following is not: 1 /
2 2 \
3 3

/**

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) {
```
 if(root == NULL)
     return true;
 
 return checkSymmetric(root->left, root->right);
```
}

bool checkSymmetric(TreeNode* left, TreeNode* right) { if(left == NULL && right == NULL) return true; if(left == NULL || right == NULL) return false;
```
 return (left->val == right->val) && checkSymmetric(left->left, right->right) && checkSymmetric(right->left, left->right);
```
} };