From 9663ae26c683a6d706eea089ac78c8e86fe8ce59 Mon Sep 17 00:00:00 2001
From: daviddoji <daviddoji@pm.me>
Date: Sat, 12 Mar 2022 19:23:02 +0100
Subject: [PATCH] Solution to problem 7 in Python

---
 src/Year_2016/P7.py | 58 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 52 insertions(+), 6 deletions(-)

diff --git a/src/Year_2016/P7.py b/src/Year_2016/P7.py
index b1a6728..f419adb 100644
--- a/src/Year_2016/P7.py
+++ b/src/Year_2016/P7.py
@@ -22,9 +22,6 @@
 
 # How many IPs in your puzzle input support TLS?
 
-# from collections import deque
-# from itertools import islice #tee
-
 import re
 
 with open("files/P7.txt") as f:
@@ -41,13 +38,62 @@ def abba(s: str) -> bool:
 
 
 def part_1() -> None:
-    count = 0
+    tls = 0
     for ip in IPs:
         sn, hn = (" ".join(ip[::2]), " ".join(ip[1::2]))
         if abba(sn) and not (abba(hn)):
-            count += 1
-    print(count)
+            tls += 1
+
+    print(f"There are {tls} IPs supporting TLS")
+
+
+# --- Part Two ---
+
+# You would also like to know which IPs support SSL (super-secret listening).
+
+# An IP supports SSL if it has an Area-Broadcast Accessor, or ABA, anywhere in
+# the supernet sequences (outside any square bracketed sections), and a
+# corresponding Byte Allocation Block, or BAB, anywhere in the hypernet
+# sequences. An ABA is any three-character sequence which consists of the same
+# character twice with a different character between them, such as xyx or aba.
+# A corresponding BAB is the same characters but in reversed positions: yxy and
+# bab, respectively.
+
+# For example:
+
+#     aba[bab]xyz supports SSL (aba outside square brackets with corresponding
+# bab within square brackets).
+#     xyx[xyx]xyx does not support SSL (xyx, but no corresponding yxy).
+#     aaa[kek]eke supports SSL (eke in supernet with corresponding kek in
+# hypernet; the aaa sequence is not related, because the interior character
+# must be different).
+#     zazbz[bzb]cdb supports SSL (zaz has no corresponding aza, but zbz has a
+# corresponding bzb, even though zaz and zbz overlap).
+
+# How many IPs in your puzzle input support SSL?
+
+
+def is_aba(s: str) -> list[str]:
+    aba_list = []
+    for i0, i1, i2 in zip(s, s[1:], s[2:]):
+        if i0 == i2 and i0 != i1:
+            aba_list.append("".join([i0, i1, i2]))
+    return aba_list
+
+
+def part_2() -> None:
+    ssl = 0
+    for ip in IPs:
+        sn, hn = (" ".join(ip[::2]), " ".join(ip[1::2]))
+        aba_list = is_aba(sn)
+        for aba in aba_list:
+            if aba[1] + aba[0] + aba[1] in hn:
+                ssl += 1
+                break
+
+    print(f"There are {ssl} IPs supporting SSL")
 
 
 if __name__ == "__main__":
     part_1()
+    part_2()