LeetCode_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 {
public:
   void DFS(TreeNode *root, vector<int> &temp, int tempSum)
    {
        if(root->left == NULL && root -> right== NULL && tempSum == sum) {
                result.push_back(temp);
                return;
        }

        if(root->left!= NULL ){
            temp.push_back(root->left->val);
            DFS(root->left, temp,root->left->val + tempSum );
            temp.pop_back();
        }

        if(root->right != NULL ){
            temp.push_back(root->right->val);
            DFS(root->right, temp, root->right->val + tempSum);
            temp.pop_back();
        }
    }
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        result.clear();
        if(!root) return result;
        this->sum = sum;
        vector<int> temp;
        temp.push_back(root->val);
        DFS(root, temp, root->val);
        return result;
    }
private:
    int sum;
    vector<vector<int>> result;
};