leetcode257-二叉树的所有路径

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<string> res;
    void Tracking(TreeNode* root,string sss)
    {
        if(root==nullptr) return;
        sss += ("->" + to_string(root->val));
        Tracking(root->left,sss);
        Tracking(root->right,sss);
        if(!root->left&&!root->right) res.push_back(sss);
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        if(!root->left&&!root->right) return {to_string(root->val)};
        Tracking(root->left,to_string(root->val));
        Tracking(root->right,to_string(root->val));
        return res;
    }
};