LeetCode 257. Binary Tree Paths

Problem

题目链接

Solution

此题题意为，给定一棵二叉树，要求你找出所有根到叶节点的路径，题目也没有对访问次序做要求。
那么我们只要简单地对整棵树做DFS就行了。

/**
 * 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:
    void dfs(vector<string> &ans,TreeNode* root,string path){
        if(root==NULL) return;
        path+=to_string(root->val);
        if(root->left==NULL && root->right==NULL) ans.push_back(path);
        else path+="->";
        dfs(ans,root->left,path);
        dfs(ans,root->right,path);
        return;
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<string> ans;
        string path="";
        dfs(ans,root,path);
        return ans;
    }
};

Result