Add solution to 2024-12-12

Author: fuglede

2024/day12/solutions.py

@@ -0,0 +1,28 @@
+import networkx as nx
+
+
+with open("input") as f:
+    board = {
+        i + 1j * j: x
+        for i, l in enumerate(f.read().strip().split("\n"))
+        for j, x in enumerate(l)
+    }
+
+fourdir = {1, -1, 1j, -1j}
+G = nx.Graph(
+    (z, z + dz) for z in board for dz in fourdir if board[z] == board.get(z + dz)
+)
+G.add_nodes_from(board)
+
+res1 = res2 = 0
+for comp in nx.connected_components(G):
+    wall = {(z, dz * 1j) for dz in fourdir for z in comp if z + dz not in comp}
+
+    res1 += len(comp) * len(wall)
+    res2 += len(comp) * sum((z + dz, dz) not in wall for (z, dz) in wall)
+
+# Part 1
+print(res1)
+
+# Part 2
+print(res2)