public class Problem113Solution3 {
    List<List<Integer>> result = new ArrayList<>();
    LinkedList<Integer> path = new LinkedList<>();

    public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
        traversal(root, targetSum);
        return result;
    }

    public void traversal(TreeNode treeNode, int targetSum) {
        if (treeNode == null) {
            return;
        }

        path.add(treeNode.val);
        targetSum -= treeNode.val;

        if (treeNode.left == null && treeNode.right == null && targetSum == 0) {
            result.add(new ArrayList<>(path));
        }

        traversal(treeNode.left, targetSum);
        traversal(treeNode.right, targetSum);
        path.pollLast();
    }

    class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }
}