Day 23, 2024 - Tweaks

2024/day23/day23.py

@@ -2,66 +2,35 @@
 
 import sys
 from collections import defaultdict
-from itertools import combinations
+
+
+def find_connections(c, seq):
+    for n in g[c]:
+        if n > c:
+            newseq = seq + (n,)
+            if set(newseq).issubset(g[n]):
+                results.add(newseq)
+                find_connections(n, newseq)
 
 lines = sys.stdin.read().strip().split('\n')
 
 g = defaultdict(set)
 
 for line in lines:
     a,b = line.split('-')
-    g[a].add(b)
-    g[b].add(a)
-
-def part1():
-
-    ans = 0
-    for p in combinations(g, r=3):
-        if not any(c.startswith('t') for c in p):
-            continue
-
-        a,b,c = p
-        sa = {a} | g[a]
-        sb = {b} | g[b]
-        sc = {c} | g[c]
-
-        if set(p).issubset(sa & sb & sc):
-            ans += 1
-    return ans
+    g[a] |= {a, b}
+    g[b] |= {a, b}
 
 results = set()
 
-def all_shared(nodes):
-    return all(set(nodes).issubset(g[n]) for n in nodes)
-
-def find_pools(c, seq=tuple()):
-    if not seq:
-        seq = (c,)
-
-    for n in g[c]:
-        if n <= c: # avoid exploring the same route twice
-            continue
-        newseq = seq + (n,)
-        if all_shared(newseq):
-            results.add(tuple(sorted(newseq)))
-            find_pools(n, newseq)
-
-def part2():
-    for c in g:
-        g[c].add(c)
-
-    for c in g:
-        find_pools(c)
-
-    ans = sorted(max(results, key=len))
-    return ','.join(ans)
-
+for c in g:
+    find_connections(c, (c,))
 
-# a1 = part1()
-# print('part1:', a1)
+a1 = sum(len(p) == 3 and any(n.startswith('t') for n in p) for p in results)
+print('part1:', a1)
 
-a2 = part2()
+a2 = ','.join(max(results, key=len))
 print('part2:', a2)
 
-# assert a1 == 1062
+assert a1 == 1062
 assert a2 == 'bz,cs,fx,ms,oz,po,sy,uh,uv,vw,xu,zj,zm'