Solution.cpp

/**
 * 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> ans;

    vector<string> binaryTreePaths(TreeNode* root) {
        dfs(root, "");
        return ans;
    }

    void dfs(TreeNode* root, string t) {
        t += to_string(root->val);
        if (!root->left && !root->right)
        {
            ans.push_back(t);
            return;
        }
        t += "->";
        if (root->left) dfs(root->left, t);
        if (root->right) dfs(root->right, t);
    }
};