Add solution to 2024-12-05

Author: fuglede

2024/day05/solutions.py

@@ -0,0 +1,35 @@
+import networkx as nx
+
+with open("input") as f:
+    gs = f.read().strip().split("\n\n")
+
+rules = [tuple(map(int, l.split("|"))) for l in gs[0].split("\n")]
+updates = [tuple(map(int, l.split(","))) for l in gs[1].split("\n")]
+
+unsorted_updates = {
+    update
+    for update in updates
+    if any(
+        a in update and b in update and update.index(a) > update.index(b)
+        for a, b in rules
+    )
+}
+
+# Part 1
+print(
+    sum(
+        update[len(update) // 2] for update in updates if update not in unsorted_updates
+    )
+)
+
+# Part 2
+sorted_updates = [
+    list(
+        nx.topological_sort(
+            nx.DiGraph((a, b) for a, b in rules if a in update and b in update)
+        )
+    )
+    for update in unsorted_updates
+]
+
+print(sum(update[len(update) // 2] for update in sorted_updates))