class Solution {
public:
    vector<string> binaryTreePaths(TreeNode* root) {
        function<void(TreeNode*, string)> get_path= [&](TreeNode* root, string path) {
            if(root == nullptr) return ;
            path += to_string(root->val);
            if(root->left == nullptr && root->right == nullptr) {
                res.push_back(path);
            }
            else {
                path += "->";
            }   
            get_path(root->left,  path);
            get_path(root->right, path);
        };
        get_path(root, "");
        return res;
    }
private:
    vector<string> res;
};