Path Sum II

/**
 * 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<vector<int> > sumpath;  
         int refsum;
public:
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sumpath.clear();
        if(root==NULL)
        return sumpath;
        refsum = sum;
        vector<int> path;
        allpath(root,0,path);
        return sumpath;
    }
    
    void allpath(TreeNode *root,int pre,vector<int> path)
    {
        if(root->left==NULL&&root->right==NULL)
        {
            if(pre+root->val==refsum)
            {
                path.push_back(root->val);
                sumpath.push_back(path);
            }
        }
        path.push_back(root->val);
        if(root->left!=NULL)
        {
            allpath(root->left,pre+root->val,path);
        }
        if(root->right!=NULL)
        {
            
            allpath(root->right,pre+root->val,path);
        }
    }
};