2016: d12: ex2: add solution

2016/d12/ex2/ex2.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python
+
+import enum
+import sys
+from typing import NamedTuple
+
+
+class Op(enum.StrEnum):
+    CPY = "cpy"
+    INC = "inc"
+    DEC = "dec"
+    JNZ = "jnz"
+
+
+class Instruction(NamedTuple):
+    op: Op
+    x: str
+    y: str | None = None
+
+    @classmethod
+    def from_str(cls, input: str) -> "Instruction":
+        op, *rest = input.split()
+        return cls(Op(op), *rest)
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> list[Instruction]:
+        return [Instruction.from_str(line) for line in input.splitlines()]
+
+    def fibonacci(n: int) -> int:
+        a, b = 1, 1
+        for _ in range(n):
+            a, b = b, a + b
+        return b
+
+    instructions = parse(input)
+    fib_n = int(instructions[2].x) + int(instructions[5].x)
+    mult = int(instructions[16].x)
+    fact = int(instructions[17].x)
+    return fibonacci(fib_n) + mult * fact
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()