Leetcode:Symmetric Tree 判断对称树

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:

 

    1
   / \
  2   2
 / \ / \
3  4 4  3

But the following is not:

    1
   / \
  2   2
   \   \
   3    3

 

解题分析：

二叉树递归，始终是第一颗二叉树的左子树和第二颗二叉树的右子树相比较

class Solution {
public:
    bool isSymmetric(TreeNode *root) {
        if (root == nullptr) return true;
        return SymmeFunc(root->left, root->right);
    }
    bool SymmeFunc(TreeNode* left, TreeNode* right) {
        if (left == nullptr && right == nullptr) {
            return true;
        } else if (left != nullptr && right != nullptr) {
            return ((left->val == right->val) && SymmeFunc(left->left, right->right) && SymmeFunc(left->right, right->left));
        } else {
            return false;
        }
    }
};