import java.util.ArrayList; import java.util.LinkedList; import java.util.List; public class PathSumII { public List> pathSum(TreeNode root, int sum) { List> result = new LinkedList<>(); helper(root, sum, result, new LinkedList<>()); return result; } private void helper(TreeNode node, int sum, List> result, List list) { if (node == null) { return; } list.add(node.val); if (node.left == null && node.right == null && sum == node.val) { result.add(new ArrayList<>(list)); } else { helper(node.left, sum - node.val, result, list); helper(node.right, sum - node.val, result, list); } list.remove(list.size() - 1); } }