2024 day 5

puzzles/Y2024/D5/p1.py

@@ -0,0 +1,26 @@
+from typing import Any
+from collections import defaultdict
+
+
+def puzzle(input: str) -> Any:
+    s = input.split("\n\n")
+    rules = [list(map(int, rule.split("|"))) for rule in s[0].strip().splitlines()]
+    updates = [
+        list(map(int, update.split(","))) for update in s[1].strip().splitlines()
+    ]
+
+    # map of every number to the set of every number it must come before
+    before = defaultdict(set)
+    for rule in rules:
+        before[rule[0]].add(rule[1])
+
+    sum = 0
+    for update in updates:
+        seen: set[int] = set()
+        for num in update:
+            if len(seen.intersection(before[num])) != 0:
+                break
+            seen.add(num)
+        else:
+            sum += update[len(update) // 2]
+    return sum

puzzles/Y2024/D5/p2.py

@@ -0,0 +1,32 @@
+from typing import Any
+from collections import defaultdict
+from functools import cmp_to_key
+
+
+def puzzle(input: str) -> Any:
+    s = input.split("\n\n")
+    rules = [list(map(int, rule.split("|"))) for rule in s[0].strip().splitlines()]
+    updates = [
+        list(map(int, update.split(","))) for update in s[1].strip().splitlines()
+    ]
+
+    # map of every number to the set of every number it must come before
+    before = defaultdict(set)
+    for rule in rules:
+        before[rule[0]].add(rule[1])
+
+    def compare(a: int, b: int) -> int:
+        if b in before[a]:
+            return -1
+        return 0
+
+    sum = 0
+    for update in updates:
+        seen: set[int] = set()
+        for num in update:
+            if len(seen.intersection(before[num])) != 0:
+                update.sort(key=cmp_to_key(compare))
+                sum += update[len(update) // 2]
+                break
+            seen.add(num)
+    return sum