Bitmask in Python with Tests

Bitmask holds 15 problems (7 Medium, 8 Hard). Generate any of them into the current directory with lcpy gen -n <number>.

#	Problem	Difficulty	Solution
351	Android Unlock Patterns	Medium	solution.py
464	Can I Win	Medium	solution.py
465	Optimal Account Balancing	Hard	solution.py
473	Matchsticks to Square	Medium	solution.py
526	Beautiful Arrangement	Medium	solution.py
638	Shopping Offers	Medium	solution.py
691	Stickers to Spell Word	Hard	solution.py
698	Partition to K Equal Sum Subsets	Medium	solution.py
805	Split Array With Same Average	Hard	solution.py
847	Shortest Path Visiting All Nodes	Hard	solution.py
943	Find the Shortest Superstring	Hard	solution.py
996	Number of Squareful Arrays	Hard	solution.py
1255	Maximum Score Words Formed by Letters	Hard	solution.py
1799	Maximize Score After N Operations	Hard	solution.py
2002	Maximum Product of the Length of Two Palindromic Subsequences	Medium	solution.py