[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
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public List<List<Integer>> pathSum(TreeNode root, int sum) {
         List<List<Integer>> result=new ArrayList<List<Integer>>();
        List<Integer> tmp=new ArrayList<Integer>();
        dfs(result,tmp,sum,root,0);
        return result;
    }

    private void dfs(List<List<Integer>> result, List<Integer> tmp, int sum, TreeNode root, int curSum) {
        // TODO Auto-generated method stub
        if(root==null)
            return;
        if(root.left==null&&root.right==null){
            if(curSum+root.val==sum){
                tmp.add(root.val);
                result.add(new ArrayList<Integer>(tmp));
                tmp.remove(tmp.size()-1);
                return;
            }
            return;
        }
        tmp.add(root.val);
        dfs(result,tmp,sum,root.left,curSum+root.val);
        dfs(result,tmp,sum,root.right,curSum+root.val);
        tmp.remove(tmp.size()-1);
    }
}