From 7cb89fe4164c63eaafeb7542030af187a5e32a68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustav=20S=C3=B6rn=C3=A4s?= <gustav@sornas.net>
Date: Sat, 12 Dec 2020 07:06:43 +0100
Subject: day 12

---
 20/README    |  2 ++
 20/py/d12.py | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 20/py/d12.py

(limited to '20')

diff --git a/20/README b/20/README
index 65c94cf..a289864 100644
--- a/20/README
+++ b/20/README
@@ -13,6 +13,7 @@ Day     Time            Ans     Time            Ans
   9    2.741       26796446    2.875        3353494
  10    0.027           2046    0.161  1157018619904
  11  432.343           2338  580.579           2134
+ 12    0.257           1645    0.279          35292
       -------                 -------
 tot    TBD                     TBD
 
@@ -21,6 +22,7 @@ Stats:
 
       -------Part 1--------   -------Part 2--------
 Day       Time  Rank  Score       Time  Rank  Score
+ 12   00:09:08   645      0   00:16:03   373      0
  11   00:55:39  4799      0   01:20:27  4040      0
  10   00:08:17  1496      0   00:51:01  2766      0
   9   00:25:55  6220      0   00:31:44  4392      0
diff --git a/20/py/d12.py b/20/py/d12.py
new file mode 100644
index 0000000..4057c7b
--- /dev/null
+++ b/20/py/d12.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+import aoc20
+import sys
+
+
+def pt1(_in):
+    x, y = 0, 0
+    dirs = ((1, 0), (0, -1), (-1, 0), (0, 1))
+    dir = 0
+    for inst in _in:
+        action, amount = inst[0], int(inst[1:])
+        if action == "N":
+            y -= amount
+        elif action == "W":
+            x -= amount
+        elif action == "S":
+            y += amount
+        elif action == "E":
+            x += amount
+        elif action == "F":
+            x += dirs[dir][0] * amount
+            y += dirs[dir][1] * amount
+        elif action == "L":
+            dir = (dir + amount // 90) % 4
+        elif action == "R":
+            dir = (dir - amount // 90) % 4
+    return abs(x) + abs(y)
+
+
+def pt2(_in):
+    ship_x, ship_y = 0, 0
+    wp_x, wp_y = 10, -1
+    for inst in _in:
+        action, amount = inst[0], int(inst[1:])
+        if action == "N":
+            wp_y -= amount
+        elif action == "W":
+            wp_x -= amount
+        elif action == "S":
+            wp_y += amount
+        elif action == "E":
+            wp_x += amount
+        elif action == "F":
+            ship_x += wp_x * amount
+            ship_y += wp_y * amount
+        elif action == "L":
+            for _ in range((amount//90) % 4):
+                wp_x, wp_y = wp_y, -wp_x
+        elif action == "R":
+            for _ in range((amount//90) % 4):
+                wp_x, wp_y = -wp_y, wp_x
+    return abs(ship_x) + abs(ship_y)
+
+
+if __name__ == "__main__":
+    input = aoc20.read_input(sys.argv[1:], 12)
+    print(pt1(input))
+    print(pt2(input))
-- 
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