porting over AOC from previous years to a monorepo.

2020/days/02/day2.py

@@ -0,0 +1,51 @@
+#! /usr/bin/env python3
+
+import pathlib
+import sys
+import re
+from dataclasses import dataclass
+
+@dataclass
+class PasswordSpec:
+    first:int
+    second:int
+    letter:str
+    password:str
+
+def parse(puzzle_input: str):
+    """Parse input"""
+    regex = re.compile(r'^(\d+)-(\d+) (\w): (\w+)$')
+    toInt = lambda x: PasswordSpec(int(x[0]), int(x[1]), x[2], x[3])
+    return [toInt(regex.match(i).groups()) for i in puzzle_input.splitlines()]
+
+def part1(data):
+    """Solve part 1"""
+    test = lambda x: x.first<=x.password.count(x.letter)<=x.second
+    # these two lines are equivilant.
+    # return sum(1 for p in data if test(p))
+    return len([1 for p in data if test(p)])
+
+def test_password(passwordSpec: PasswordSpec):
+    if passwordSpec.password[passwordSpec.first-1]==passwordSpec.letter:
+        return passwordSpec.password[passwordSpec.second-1]!=passwordSpec.letter
+    else:
+        return passwordSpec.password[passwordSpec.second-1]==passwordSpec.letter
+
+def part2(data):
+    """Solve part 2"""
+    return sum(1 for p in data if test_password(p))
+
+def solve(puzzle_input):
+    """Solve the puzzle for the given input"""
+    data = parse(puzzle_input)
+    solution1 = part1(data)
+    solution2 = part2(data)
+
+    return solution1, solution2
+
+if __name__ == "__main__":
+    for path in sys.argv[1:]:
+        print(f"{path}:")
+        puzzle_input = pathlib.Path(path).read_text().strip()
+        solutions = solve(puzzle_input)
+        print("\n".join(str(solution) for solution in solutions))