二叉树中和为某一个值的路径

import java.util.ArrayList;
import java.util.List;

class Solution_34 {

    public static void main(String[] args) {
        TreeNode root = new TreeNode(5);
        root.left = new TreeNode(4);
        root.right = new TreeNode(8);
        root.left.left = new TreeNode(11);
        root.left.left.left = new TreeNode(7);
        root.left.left.right = new TreeNode(2);
        root.right.left = new TreeNode(13);
        root.right.right = new TreeNode(4);
        root.right.right.left = new TreeNode(5);
        root.right.right.right = new TreeNode(1);
        List<List<Integer>> lists = new Solution_34().pathSum(root, 22);
        System.out.println(lists);
    }


    public List<List<Integer>> pathSum(TreeNode root, int sum) {
        List<List<Integer>> lists = new ArrayList<>();
        if (root==null) return lists;
        ArrayList<Integer>  local = new ArrayList<>();
        help(lists,local,root,sum);
        return lists;
    }

    private void help(List<List<Integer>> lists, ArrayList<Integer> local, TreeNode node, int sum) {
        local.add(node.val);
        if (node.left ==null && node.right == null){
            ArrayList<Integer> oldlocal = new ArrayList<>(local);
            int Sum = 0;
            Sum  = local.stream().reduce(Sum, (a, b) -> a + b);
            if (Sum == sum){
                lists.add(oldlocal);
            }
        }
        if (node.left!=null) {
            help(lists, local, node.left, sum);
            local.remove(local.size() - 1);
        }
        if (node.right!=null) {
            help(lists, local, node.right, sum);
            local.remove(local.size() - 1);
        }

    }
}