Path Sum II

/**
 * Definition for a binary tree node.
 * 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) {
        if(root==NULL)
            return res;
        vector<int> temp;
        work(root,sum,temp);
        return res;
    }
    
    vector<vector<int>> res;
    
    void work(TreeNode * root,int sum,vector<int> temp){
        
        temp.push_back(root->val);
        if(root->left==NULL&&root->right==NULL)
        {
            if(sum==root->val)
            {
                res.push_back(temp);
            }
            return ; 
        }
        if(root->left!=NULL)
        {
            work(root->left,sum-(root->val),temp);
        }
        if(root->right!=NULL)
        {
            work(root->right,sum-(root->val),temp);
        }
    }
    
};