Path Sum II(leetcode)

题目：

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.
For example:

Given the below binary tree and

sum
= 22

,

5
/ \
4   8
/   / \
11  13  4
/  \    / \
7    2  5   1

return

[
[5,4,11,2],
[5,8,4,5]
]

题目来源：https://oj.leetcode.com/problems/path-sum-ii/

解题思路：用先序遍历进行深搜

#include<iostream>
#include<vector>
using namespace std;

struct TreeNode
{
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
//先序遍历
void dfs(TreeNode *root,int temp,vector<int> &result,vector<vector<int> > &results,int sum)
{
if(root==NULL)
return ;
temp+=root->val;
result.push_back(root->val);
if(root->left==NULL && root->right==NULL)
{
if(temp==sum)
{
results.push_back(result);
result.pop_back();
return ;
}
}
dfs(root->left,temp,result,results,sum);
dfs(root->right,temp,result,results,sum);
result.pop_back();
}

vector<vector<int> > pathSum(TreeNode *root, int sum)
{
vector<vector<int> >results;
if(root==NULL)
return results;
vector<int> result;
dfs(root,0,result,results,sum);
return results;
}

int main()
{
TreeNode *root=new TreeNode(-2);
//	root->left=new TreeNode(2);
root->right=new TreeNode(-3);
vector<vector<int> > results=pathSum(root,-5);

system("pause");
return 0;
}