1 files changed, 58 insertions, 0 deletions
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))