treewide: fix 'ruff check' errors

This is mostly about unused imports.

A couple errors remain, but are fine in my book (using `l` as a variable
name, assigning a lambda to a variable).

2021/d01/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List
 

2021/d02/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List
 

2021/d02/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List
 

2021/d03/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List
 

2021/d03/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from copy import deepcopy
 from typing import List

2021/d06/ex1/ex1.py

@@ -3,7 +3,6 @@
 import itertools
 import sys
 from collections import Counter
-from dataclasses import dataclass
 from typing import Iterator, List, TypeVar
 
 T = TypeVar("T")

2021/d06/ex2/ex2.py

@@ -3,7 +3,6 @@
 import itertools
 import sys
 from collections import Counter
-from dataclasses import dataclass
 from typing import Iterator, List, TypeVar
 
 T = TypeVar("T")

2021/d07/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List
 

2021/d07/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from math import ceil, floor
 from typing import List

2021/d08/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from dataclasses import dataclass
 from typing import Dict, List, Set

2021/d09/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import Iterator, List, Tuple
 

2021/d09/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import Iterator, List, Tuple
 

2021/d10/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import List, Optional, cast
 

2021/d10/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from typing import Iterator, List, Optional
 

2021/d11/ex1/ex1.py

@@ -2,7 +2,6 @@
 
 import itertools
 import sys
-from copy import deepcopy
 from typing import Iterator, List, Set, Tuple
 
 Grid = List[List[int]]

2021/d11/ex2/ex2.py

@@ -2,7 +2,6 @@
 
 import itertools
 import sys
-from copy import deepcopy
 from typing import Iterator, List, Set, Tuple
 
 Grid = List[List[int]]

2021/d12/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from collections import defaultdict
 from typing import Dict, List, Set

2021/d12/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
 import sys
 from collections import defaultdict
 from typing import Dict, List, Set

2021/d15/ex1/ex1.py

@@ -1,9 +1,8 @@
 #!/usr/bin/env python
 
 import heapq
-import itertools
 import sys
-from typing import Iterator, List, NamedTuple, Set, Tuple
+from typing import Iterator, List, NamedTuple, Set
 
 
 class Point(NamedTuple):

2021/d15/ex2/ex2.py

@@ -1,9 +1,8 @@
 #!/usr/bin/env python
 
 import heapq
-import itertools
 import sys
-from typing import Iterator, List, NamedTuple, Set, Tuple
+from typing import Iterator, List, NamedTuple, Set
 
 
 class Point(NamedTuple):

2021/d16/ex1/ex1.py

@@ -5,7 +5,7 @@ import functools
 import itertools
 import sys
 from dataclasses import dataclass
-from typing import Iterable, Iterator, List, Tuple, TypeVar
+from typing import Iterable, Iterator, List, Tuple
 
 RawPacket = List[bool]
 

2021/d16/ex2/ex2.py

@@ -6,7 +6,7 @@ import itertools
 import math
 import sys
 from dataclasses import dataclass
-from typing import Callable, Dict, Iterable, Iterator, List, Tuple, TypeVar
+from typing import Callable, Dict, Iterable, Iterator, List, Tuple
 
 RawPacket = List[bool]
 

2021/d17/ex1/ex1.py

@@ -1,7 +1,6 @@
 #!/usr/bin/env python
 
 import itertools
-import math
 import sys
 from typing import Iterator, List, NamedTuple
 

2021/d17/ex2/ex2.py

@@ -1,7 +1,5 @@
 #!/usr/bin/env python
 
-import itertools
-import math
 import sys
 from typing import Iterator, List, NamedTuple
 

2021/d18/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import functools
 import itertools
 import sys
 from copy import deepcopy

2021/d19/ex1/ex1.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import functools
 import itertools
 import sys
 from dataclasses import dataclass

2021/d19/ex2/ex2.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 
-import functools
 import itertools
 import sys
 from dataclasses import dataclass

2021/d22/ex1/ex1.py

@@ -3,7 +3,7 @@
 import functools
 import itertools
 import sys
-from typing import Iterator, List, NamedTuple, Optional, Set, Tuple, cast
+from typing import List, NamedTuple, Optional, Set, Tuple
 
 
 class Point(NamedTuple):

2021/d22/ex2/ex2.py

@@ -3,7 +3,7 @@
 import functools
 import itertools
 import sys
-from typing import Iterator, List, NamedTuple, Optional, Set, Tuple, cast
+from typing import List, NamedTuple, Optional, Set, Tuple
 
 
 class Point(NamedTuple):

2021/d23/ex1/ex1.py

@@ -3,7 +3,7 @@
 import enum
 import functools
 import sys
-from typing import Iterator, List, NamedTuple, Optional, Tuple, cast
+from typing import Iterator, List, NamedTuple, Optional, Tuple
 
 
 class Point(NamedTuple):

2021/d23/ex2/ex2.py

@@ -3,7 +3,7 @@
 import enum
 import functools
 import sys
-from typing import Iterator, List, NamedTuple, Optional, Tuple, cast
+from typing import Iterator, List, NamedTuple, Optional, Tuple
 
 
 class Point(NamedTuple):

2021/d25/ex1/ex1.py

@@ -1,9 +1,8 @@
 #!/usr/bin/env python
 
-import enum
 import itertools
 import sys
-from typing import Iterable, Iterator, List, NamedTuple, Set
+from typing import List, NamedTuple, Set
 
 
 class Point(NamedTuple):