day 8, generators are faster (2x)

d08/run.py

@@ -0,0 +1,22 @@
+import sys
+from itertools import cycle
+from math import lcm
+
+I, _, *P = [l for l in sys.stdin.read().splitlines()]
+# 0000000000111111111
+# 0123456789012345678
+# BCN = (HFN, KFC)
+P = {l[0:3]:(l[7:10],l[12:15]) for l in P}
+
+def countsteps(g):
+    C = g
+    N = 0
+    for i in cycle(I):
+        if C[2] == 'Z':
+            break
+        C = P[C][i == 'R']
+        N += 1
+    return N
+
+print("part 1:", countsteps("AAA"))
+print("part 2:", lcm(*(countsteps(p) for p in P.keys() if p[2] == 'A')))