From 139f3db14fb3029a3e670765c53126386f943574 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 12 Dec 2020 10:06:00 +0100
Subject: [PATCH] 2020: d12: ex1: add solution

---
 2020/d12/ex1/ex1.py | 53 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100755 2020/d12/ex1/ex1.py

diff --git a/2020/d12/ex1/ex1.py b/2020/d12/ex1/ex1.py
new file mode 100755
index 0000000..6d74574
--- /dev/null
+++ b/2020/d12/ex1/ex1.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+
+import sys
+from typing import List, Tuple
+
+Positiom = Tuple[str, int, int]
+Instruction = Tuple[str, int]
+
+ORIENTATIONS = ["N", "W", "S", "E"]
+MOVES = {
+    "N": (1, 0),
+    "W": (0, -1),
+    "S": (-1, 0),
+    "E": (0, 1),
+}
+
+
+def move_ship(pos: Positiom, instr: Instruction) -> Positiom:
+    if instr[0] == "L":
+        assert instr[1] % 90 == 0  # Sanity check
+        delt = instr[1] // 90
+        orientation = ORIENTATIONS[
+            (ORIENTATIONS.index(pos[0]) + delt) % len(ORIENTATIONS)
+        ]
+        return (orientation, *pos[1:])
+    elif instr[0] == "R":
+        assert instr[1] % 90 == 0  # Sanity check
+        delt = instr[1] // 90
+        orientation = ORIENTATIONS[ORIENTATIONS.index(pos[0]) - delt]
+        return (orientation, *pos[1:])
+    else:
+        dx, dy = MOVES[pos[0] if instr[0] == "F" else instr[0]]
+        x, y = pos[1], pos[2]
+        x += dx * instr[1]
+        y += dy * instr[1]
+        return (pos[0], x, y)
+
+
+def solve(raw: List[str]) -> int:
+    instructions = [(i[0], int(i[1:])) for i in raw]
+    ship = ("E", 0, 0)
+    for i in instructions:
+        ship = move_ship(ship, i)
+    return abs(ship[1]) + abs(ship[2])
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()