2020 day 17

2020/d17.py

@@ -0,0 +1,42 @@
+from itertools import product
+from lib import get_data
+from collections import defaultdict
+
+data = get_data(__file__)
+
+
+def neighbors(p):
+    d = len(p)
+    for xs in product(range(-1, 2), repeat=d):
+        if all(x == 0 for x in xs):
+            continue
+        yield tuple([p[i] + xs[i] for i in range(len(xs))])
+
+
+for d in [3, 4]:
+    points = set()
+    lines = data.splitlines()
+    for y in range(len(lines)):
+        for x in range(len(lines[0])):
+            if lines[y][x] == "#":
+                points.add(tuple([x, y] + [0] * (d - 2)))
+
+    for _ in range(6):
+        new_points = set()
+        actives = defaultdict(int)
+        for p in points:
+            nbcount = 0
+            for nb in neighbors(p):
+                actives[nb] += 1
+                if nb in points:
+                    nbcount += 1
+            if nbcount == 2 or nbcount == 3:
+                new_points.add(p)
+        for p, count in actives.items():
+            if p in points:
+                continue
+            elif count == 3:
+                new_points.add(p)
+        points = new_points
+
+    print(len(points))

README.md

@@ -155,7 +155,8 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 14: 40:26 (Made a bunch of mistakes even misunderstanding Python)
 - Day 15: 17:57 (Too slow for an easy one like this)
 - Day 16: 33:00 (Not too unhappy really.)
-- Day 17:
+- Day 17: 10:00 (40th)
+- Day 18:
 
 ## AoC 2022