Day 12 13

2021/12.py

@@ -0,0 +1,17 @@
+from collections import defaultdict
+
+paths = defaultdict(list)
+for a,b in [line.split('-') for line in open("./2021/12.input").read().splitlines()]:
+    paths[a].append(b)
+    paths[b].append(a)
+
+def dfs(cave, visited, one_off):
+    if (cave == "end"): return 1
+    if (cave.islower()): visited.add(cave)
+    total = sum([dfs(i, visited, one_off) for i in paths[cave] if not i in visited])
+    total += sum([dfs(i, visited, i) for i in paths[cave] if i in visited and i != 'start']) if one_off == ' ' else 0
+    if (cave != one_off): visited.discard(cave)
+    return total;
+
+print ('Part 1:', dfs("start", set(), ''))
+print ('Part 2:', dfs("start", set(), ' '))