Leetcode题 257. 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"]

代码如下：

/**
 * 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:
    //按照容易自己习惯的数据结构来存储路径，最后做一个转换
    void findPath(TreeNode* t,vector<int>& temp, vector<vector<int> >& record)
    {
        temp.push_back(t->val);
    	if(t->left!=NULL) findPath(t->left, temp, record);
    	if(t->right!=NULL) findPath(t->right, temp, record);
    	//到达叶子节点，就记录路径
    	if(t->left==NULL && t->right==NULL)
    	{
    	    record.push_back(temp);
    	    temp.erase(temp.end()-1);
    	    return ;
    	}
    	//中间节点返回
    	temp.erase(temp.end()-1);
    	return;
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<vector<int>> record;
        vector<string> srecord;
	    if(root==NULL) return srecord;
	    vector<int> temp;
	    //找到所有的路
	    findPath(root,temp,record);
	    //把所有的路按照题目要求存储
	    string stemp;
	    for(int i=0;i<record.size();i++)
	    {
	        stringstream ss;
	        for(int j=0;j<record[i].size();j++)
	        {
	            ss<<record[i][j]<<"->";
	        }
	        stemp.clear();
	        stemp=ss.str();
	        //去掉最后的"->"
	        stemp.pop_back();
	        stemp.pop_back();
	        srecord.push_back(stemp);
	    }
	    return srecord;
    }
};