Binary Tree Paths

Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree:

All root-to-leaf paths are:[“1->2->5”, “1->3”]

分析

深度搜索

class Solution {public:    vector
      
        binaryTreePaths(TreeNode* root) {        vector
       
         ret;        string str;        dfs(ret, str, root);        return ret;    }    void dfs(vector
        
         & ret, string& str, TreeNode* root){        if (!root)            return;        if (root && !root->left&&!root->right){            str+=to_string(root->val);            ret.push_back(str);            return;        }        string tmp = str;        str += to_string(root->val)+"->";        if (root->left)            dfs(ret, str, root->left);        str = tmp;        tmp = str;        str += to_string(root->val) + "->";        if (root->right)            dfs(ret, str, root->right);        str=tmp;    }};