/**
 * 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> binaryTreePaths(TreeNode* root) {
        vector<string> res;
        string s;
        dfs(root,s,res);
        return res;

    }
    void dfs(TreeNode* root, string s, vector<string>& res){
        if(root == nullptr){ 
            return;
        }
        else s+=to_string(root->val);
        if(root->left && root->right ){
            s+="->";
            dfs(root->left,s,res);
            dfs(root->right,s,res);    
        }
        else if(root->left || root->right){
            s+="->";
            if(root->left) dfs(root->left,s,res);
            if(root->right) dfs(root->right,s,res);
        } 
        else res.emplace_back(s);
    }
};