From 595db92c73fbe936c49866c84fa0e65fec9fdfa2 Mon Sep 17 00:00:00 2001
From: dece <shgck@pistache.land>
Date: Sun, 27 Dec 2020 15:19:53 +0100
Subject: [PATCH] Day 24

---
 2020/day24.py | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 2020/day24.py

diff --git a/2020/day24.py b/2020/day24.py
new file mode 100644
index 0000000..8b92e9c
--- /dev/null
+++ b/2020/day24.py
@@ -0,0 +1,65 @@
+import sys
+
+from grid import Grid
+
+def main():
+    lines = [line.rstrip() for line in sys.stdin]
+    g = Grid(value_factory=int)
+
+    # Part 1
+    for line in lines:
+        x, y = 0, 0
+        while line:
+            if line[0] in ("e", "w"):
+                x, y = move(x, y, line[0])
+                line = line[1:]
+            else:
+                x, y = move(x, y, line[:2])
+                line = line[2:]
+        g.setv(x, y, abs(g.getv(x, y) - 1))
+    print("Black tiles:", sum(v for _, _, v in g.values_gen()))
+
+    # Part 2 aka stop using this grid class it's horrible
+    for _ in range(100):
+        expand(g)
+        yagol(g)
+    print("Black tiles p2:", sum(v for _, _, v in g.values_gen()))
+
+def move(x, y, d):
+    if d in ("e", "w"):
+        x += 1 if d == "e" else -1
+    else:
+        dy, dx = d[0], d[1]
+        if y % 2 == 0 and dx == "w":
+            x -= 1
+        elif y % 2 == 1 and dx == "e":
+            x += 1
+        y += 1 if dy == "s" else -1
+    return x, y
+
+D = ["e", "se", "sw", "w", "nw", "ne"]
+
+def expand(g):
+    for x, y, _ in list(g.values_gen()):
+        for d in D:
+            dx, dy = move(x, y, d)
+            if not g.hasv(dx, dy):
+                g.setv(dx, dy, 0)
+
+def yagol(g):
+    c = {}
+    for x, y, v in g.values_gen():
+        bn = 0
+        for d in D:
+            nx, ny = move(x, y, d)
+            if g.hasv(nx, ny):
+                bn += g.getv(nx, ny)
+        if v == 1 and (bn == 0 or bn > 2):
+            c[(x, y)] = 0
+        elif v == 0 and bn == 2:
+            c[(x, y)] = 1
+    for (x, y), v in c.items():
+        g.setv(x, y, v)
+
+if __name__ == "__main__":
+    main()