From 668449e943d226c1f316df579bb6a181418ce880 Mon Sep 17 00:00:00 2001
From: cupcakearmy <hi@nicco.io>
Date: Fri, 4 Dec 2020 06:40:52 +0100
Subject: [PATCH] 4

---
 README.md             |  2 ++
 solutions/4/README.md | 14 ++++++++++++
 solutions/4/main.py   | 52 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100644 solutions/4/README.md
 create mode 100644 solutions/4/main.py

diff --git a/README.md b/README.md
index fb78acf..80cb2b3 100644
--- a/README.md
+++ b/README.md
@@ -2,4 +2,6 @@
 
 Here are my solutions for the advent of code 2020 🎄🎅
 
+Note that the exact solutions are different for some people.
+
 `/solutions/:day/*`
diff --git a/solutions/4/README.md b/solutions/4/README.md
new file mode 100644
index 0000000..561924b
--- /dev/null
+++ b/solutions/4/README.md
@@ -0,0 +1,14 @@
+# 4
+
+This one was a lot of parsing, but nothing regexp can't do.
+The first is quite straight forward, just check that all but `cid` are present.
+
+The second was a bit of validation for each field, but again some simple regexp and number checking and the job is done 🙂
+
+<details>
+  <summary>Solutions</summary>
+  <ol>
+    <li>206</li>
+    <li>123</li>
+  </ol>
+</details>
diff --git a/solutions/4/main.py b/solutions/4/main.py
new file mode 100644
index 0000000..9bed9ea
--- /dev/null
+++ b/solutions/4/main.py
@@ -0,0 +1,52 @@
+from os.path import join, dirname
+import re
+
+
+def validate_chunk(chunk, extended=False):
+    parts = re.split(' |\n', chunk.strip())
+    password = dict(map(lambda p: p.split(":"), parts))
+
+    required = ['byr', 'iyr', 'eyr', 'hgt', 'hcl', 'ecl', 'pid']
+    if not all(item in password.keys() for item in required):
+        return False
+
+    if not extended:
+        return True
+
+    if not 1920 <= int(password['byr']) <= 2002:
+        return False
+    if not 2010 <= int(password['iyr']) <= 2020:
+        return False
+    if not 2020 <= int(password['eyr']) <= 2030:
+        return False
+
+    tmp = password['hgt']
+    hgt = int(tmp[:-2])
+    unit = tmp[-2:]
+    if not unit in ['cm', 'in']:
+        return False
+    if unit == 'cm' and not 150 <= hgt <= 193:
+        return False
+    if unit == 'in' and not 59 <= hgt <= 76:
+        return False
+
+    if not re.match(r'^#[\dabcdef]{6}$', password['hcl']):
+        return False
+    if not re.match(r'^\d{9}$', password['pid']):
+        return False
+
+    if password['ecl'] not in ['amb', 'blu', 'brn', 'gry', 'grn', 'hzl', 'oth']:
+        return False
+    return True
+
+
+data = join(dirname(__file__), 'data.txt')
+with open(data) as f:
+    chunks = re.split('\n\n+', f.read().strip())
+    total_simple = 0
+    total_extended = 0
+    for chunk in chunks:
+        total_simple += int(validate_chunk(chunk))
+        total_extended += int(validate_chunk(chunk, extended=True))
+    print(f'Simple Validation:\t{total_simple}')
+    print(f'Extended Validation:\t{total_extended}')