257. Binary Tree Paths

题目：

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"]       

答案：
    和遍历类似，用递归的思路，深度优先搜索的算法
 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<string> binaryTreePaths(TreeNode* root) {
13         vector<string>str;
14         if(root==NULL){
15             return str;
16         }
17         DFS(root,"",str);
18         return str;
19     }
20     void DFS(TreeNode *node,string temp, vector<string>&str){
21         if(node->left==NULL&&node->right==NULL){
22             str.push_back(temp+to_string(node->val));
23         }
24         if(node->left!=NULL){
25             DFS(node->left,temp+to_string(node->val)+"->",str);
26         }
27         if(node->right!=NULL){
28             DFS(node->right,temp+to_string(node->val)+"->",str);
29         }
30     }
31 };


 


 






		

		
posted @ 
2016-08-02 11:12 
绵绵思远道 
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