Merge pull request #155 from ephemient/py/day23

README.md

@@ -27,4 +27,4 @@ Development occurs in language-specific directories:
 |[Day20.hs](hs/src/Day20.hs)|[Day20.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day20.kt)|[day20.py](py/aoc2024/day20.py)|[day20.rs](rs/src/day20.rs)|
 |[Day21.hs](hs/src/Day21.hs)|[Day21.kt](kt/aoc2024-lib/src/jvmCodegen/kotlin/com/github/ephemient/aoc2024/codegen/Day21.kt)|[day21.py](py/aoc2024/day21.py)|[day21.rs](rs/src/day21.rs)|
 |[Day22.hs](hs/src/Day22.hs)|[Day22.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day22.kt)|[day22.py](py/aoc2024/day22.py)|[day22.rs](rs/src/day22.rs)|
-|[Day23.hs](hs/src/Day23.hs)|[Day23.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day23.kt)|||
+|[Day23.hs](hs/src/Day23.hs)|[Day23.kt](kt/aoc2024-lib/src/commonMain/kotlin/com/github/ephemient/aoc2024/Day23.kt)|[day23.py](py/aoc2024/day23.py)||

py/aoc2024/day23.py

@@ -0,0 +1,92 @@
+"""
+Day 23: LAN Party
+"""
+
+from collections import defaultdict
+
+SAMPLE_INPUT = """
+kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn
+"""
+
+
+def _parse(data: str) -> dict[str, set[str]]:
+    graph = defaultdict(set)
+    for line in data.splitlines():
+        if "-" not in line:
+            continue
+        a, b = line.split("-", maxsplit=1)
+        graph[min(a, b)].add(max(a, b))
+        graph[max(a, b)]
+    return graph
+
+
+def part1(data: str) -> int:
+    """
+    >>> part1(SAMPLE_INPUT)
+    7
+    """
+    graph = _parse(data)
+    return sum(
+        a.startswith("t") or b.startswith("t") or c.startswith("t")
+        for a, bs in graph.items()
+        for b in bs
+        for c in graph[b]
+        if c in bs
+    )
+
+
+def part2(data: str) -> str:
+    """
+    >>> part2(SAMPLE_INPUT)
+    'co,de,ka,ta'
+    """
+    graph = _parse(data)
+
+    def _maxcomplete(used: set[str], remaining: set[str]) -> set[str]:
+        return (
+            max(
+                (
+                    _maxcomplete(used | {key}, remaining & graph[key])
+                    for key in remaining
+                ),
+                key=len,
+            )
+            if remaining
+            else used
+        )
+
+    return ",".join(sorted(_maxcomplete(set(), set(graph))))
+
+
+parts = (part1, part2)

py/pyproject.toml

@@ -46,6 +46,7 @@ day19 = "aoc2024.day19:parts"
 day20 = "aoc2024.day20:parts"
 day21 = "aoc2024.day21:parts"
 day22 = "aoc2024.day22:parts"
+day23 = "aoc2024.day23:parts"
 
 [build-system]
 requires = ["poetry-core"]