* Add new solution for the euler project problem 9 - precompute the squares. * Update sol4.py * updating DIRECTORY.md * Update sol4.py * Update sol4.py * Update sol4.py --------- Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru> Co-authored-by: MaximSmolskiy <MaximSmolskiy@users.noreply.github.com>