Binary Tree Paths

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

   1 /   \2     3 \  5

All root-to-leaf paths are:

["1->2->5", "1->3"]

二话不说，上代码：

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