Add solution to 2024-12-14

Author: fuglede

2024/day14/solutions.py

@@ -0,0 +1,45 @@
+from itertools import count
+from math import prod
+import re
+
+import numpy as np
+
+with open("input") as f:
+    ns = [list(map(int, re.findall("-?\\d+", x))) for x in f.read().strip().split("\n")]
+
+# Part 1
+w = 101
+h = 103
+qs = [0, 0, 0, 0]
+for px, py, vx, vy in ns:
+    for _ in range(100):
+        px += vx
+        py += vy
+    px %= w
+    py %= h
+    if px < w // 2 and py < h // 2:
+        qs[0] += 1
+    elif px > w // 2 and py < h // 2:
+        qs[1] += 1
+    elif px < w // 2 and py > h // 2:
+        qs[2] += 1
+    elif px > w // 2 and py > h // 2:
+        qs[3] += 1
+print(prod(qs))
+
+# Part 2
+zs = np.array([px + 1j * py for px, py, _, _ in ns])
+vs = np.array([vx + 1j * vy for _, _, vx, vy in ns])
+max_has_neighbour = 0
+
+for t in count(1):
+    zs = np.array([int(z.real) % w + (int(z.imag) % h) * 1j for z in zs + vs])
+    zs_set = set(zs)
+    num_has_neighbour = sum(z + dz in zs_set for z in zs for dz in (1, -1, 1j, -1j))
+    if num_has_neighbour > max_has_neighbour:
+        max_has_neighbour = num_has_neighbour
+        a = np.zeros((h, w), dtype=int)
+        a[zs.imag.astype(int), zs.real.astype(int)] = 1
+        print(t)
+        print("\n".join("".join(" ■"[x] for x in row) for row in a))
+        print()