Solve 2020 day 25

2020/25_crypto.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+def transform(n, loopsize):
+    return pow(n, loopsize, 20201227)
+
+def loopsize(transformed):
+    n = size = 1
+    while True:
+        n = n * 7 % 20201227
+        if n == transformed:
+            return size
+        size += 1
+
+a, b = 9789649, 3647239
+print(transform(a, loopsize(b)))