题解 | #牛群的对称排列#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
private :
    string s;;
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return bool布尔型
     */
    bool isSymmetric(TreeNode* root) {
        // write code here
        inOrder(root);
        int size = s.length();
        if (size % 2 == 0) return false; 
        int left = 0, right = size-1;
        while(left < right){
            if (s[left] == s[right]){
                left++;
                right--;
            } else {
                return false;
            }
        }
        return true;
    }

    void inOrder(TreeNode* root){
        if (root == nullptr){
      //      s.push_back('#');
            return;
        }
        inOrder(root->left);
        s.push_back(root->val + '0');
        inOrder(root->right);
    }

};