Path Sum II

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]
]

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
private:
vector<int> temp;
vector<vector<int> > ans;
public:
vector<vector<int> > pathSum(TreeNode *root, int sum) {
ans.clear();

hasPathSum(root,sum);
return ans;
}
void hasPathSum(TreeNode *root, int sum) {
if(root==NULL) return;
if(root->left==NULL && root->right==NULL)
{
if(root->val == sum)
{
temp.push_back(root->val);
ans.push_back(temp);
temp.pop_back();
}
return;
}
temp.push_back(root->val);
hasPathSum(root->left,sum - root->val);
hasPathSum(root->right,sum - root->val);
temp.pop_back();
}
};