From c0acc480e7c905a4b3cf510f3d01fc5c029557ae Mon Sep 17 00:00:00 2001
From: kamoshi <18511281+kamoshi@users.noreply.github.com>
Date: Fri, 25 Dec 2020 19:59:26 +0100
Subject: [PATCH] Create day25.py

---
 2020/Python/day25.py | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 2020/Python/day25.py

diff --git a/2020/Python/day25.py b/2020/Python/day25.py
new file mode 100644
index 0000000..78a607a
--- /dev/null
+++ b/2020/Python/day25.py
@@ -0,0 +1,38 @@
+from typing import Tuple
+
+
+def parse_pks() -> Tuple[int, int]:
+    with open("input.txt") as file:
+        return int(file.readline()), int(file.readline())
+
+
+def transform_step(value: int, subject: int) -> int:
+    value *= subject
+    value %= 20201227
+    return value
+
+
+def transform_loop(loop_value: int, subject: int) -> int:
+    value = 1
+    for _ in range(loop_value):
+        value = transform_step(value, subject)
+    return value
+
+
+def find_loop_value(subject: int, desired_value: int) -> int:
+    value = 1
+    loop = 0
+    while value != desired_value:
+        value = transform_step(value, subject)
+        loop += 1
+    return loop
+
+
+def solve_p1(public_key1: int, public_key2: int) -> int:
+    loop_value1 = find_loop_value(subject=7, desired_value=public_key1)
+    encryption_key = transform_loop(loop_value=loop_value1, subject=public_key2)
+    return encryption_key
+
+
+PK1, PK2 = parse_pks()
+print(solve_p1(public_key1=PK1, public_key2=PK2))