Leetcode: Symmetric Tree

http://oj.leetcode.com/problems/symmetric-tree/

/**
 * 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 isEqual(TreeNode *left, TreeNode *right){
        int cnt=0;
        if(left==NULL) cnt++;
        if(right==NULL) cnt++;
        if(cnt==2) return true;
        if(cnt==1) return false;
        if(left->val!=right->val) return false;
        if(isEqual(left->left,right->right)&&isEqual(left->right,right->left)) return true;
        else return false;
    }
    bool isSymmetric(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(root==NULL) return true;
        else return isEqual(root->left,root->right);
    }
};