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:  
    vector<vector<int> > pathSum(TreeNode *root, int sum) {  
          
        vector<vector<int> > gather;  
        vector<int> rootLeaf;  
        int tempSum = 0;  
        pathSum(root, tempSum, sum, gather, rootLeaf);  
        return gather;  
    }  
      
    void pathSum(TreeNode *root, int tempSum, int sum, vector<vector<int> > &gather, vector<int> rootLeaf)  
    {  
        if(root != NULL)  
        {  
            if(root->left == NULL && root->right == NULL)  
            {  
                tempSum += root->val;  
                rootLeaf.push_back(root->val);  
                if(tempSum == sum)  
                    gather.push_back(rootLeaf);  
                  
                return;  
            }  
          
            else  
            {  
                tempSum += root->val;  
                rootLeaf.push_back(root->val);  
                pathSum(root->left, tempSum, sum, gather, rootLeaf);  
                pathSum(root->right, tempSum, sum, gather, rootLeaf);  
            }  
        }  
    }  
};