From 87ce54f8380b32845bc4c7c4260b9e4f34e84dde Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Mon, 19 May 2025 20:26:02 +0100
Subject: [PATCH] 2016: d14: ex1: add solution

---
 2016/d14/ex1/ex1.py | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100755 2016/d14/ex1/ex1.py

diff --git a/2016/d14/ex1/ex1.py b/2016/d14/ex1/ex1.py
new file mode 100755
index 0000000..b960e4b
--- /dev/null
+++ b/2016/d14/ex1/ex1.py
@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+
+import functools
+import hashlib
+import itertools
+import sys
+
+
+def solve(input: str) -> int:
+    def hash(n: int, salt: str) -> str:
+        return hashlib.md5((salt + str(n)).encode()).hexdigest()
+
+    def find_triplet_char(input: str) -> str | None:
+        for i in range(0, len(input) - 2):
+            a, b, c = input[i], input[i + 1], input[i + 2]
+            if a == b and b == c:
+                return a
+        return None
+
+    salt = input.strip()
+    hashed_salt = functools.cache(functools.partial(hash, salt=salt))
+    cur_key = 0
+    for i in itertools.count():
+        candidate = hashed_salt(i)
+        if (triplet_char := find_triplet_char(candidate)) is None:
+            continue
+        for j in range(i + 1, i + 1000 + 1):
+            if (triplet_char * 5) in hashed_salt(j):
+                cur_key += 1
+                if cur_key == 64:
+                    return i
+                break
+    assert False  # Sanity check
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()