day 8, somewhat easy

part 1 realy easy
part 2 made with a trick, got from reddit megathread
else naive approach would have taken 40 day of computation

d08/part2.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()]
+Q = [l.split(' = ') for l in P ]
+P = {k:v[1:-1].split(", ") for [k,v] in Q }
+
+G = [p for p in P.keys() if p[2] == 'A' ]
+R = []
+for n,g in enumerate(G):
+    print(n+1, g, '', end='')
+    C = g
+    N = 0
+    for i in cycle(I):
+        if C[2] == 'Z':
+            break
+        C = P[C][i == 'R']
+        N += 1
+    print(N)
+    R.append(N)
+print('steps: sum:', sum(R), 'lcm:', lcm(*R))