2017: d05: ex2: add solution

2017/d05/ex2/ex2.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+
+import itertools
+import sys
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> list[int]:
+        return [int(n) for n in input.splitlines()]
+
+    instructions = parse(input)
+    offset = 0
+    for i in itertools.count():
+        if offset < 0 or offset >= len(instructions):
+            return i
+        delta = -1 if instructions[offset] >= 3 else 1
+        instructions[offset] += delta
+        offset += instructions[offset] - delta  # Account for previous increment
+    assert False  # Sanity check
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()