Add solution for day 12

AoC2021/code/AoC12.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+
+import sys
+import re
+from copy import deepcopy
+
+def parse(l):
+    groups = re.compile(r"(?P<p1>\w+)-(?P<p2>\w+)").search(l)
+    p1, p2 = groups.groups()
+    for p in (p1,p2):
+        if not p in opts.keys(): opts[p] = set()
+        if not p in opts.keys(): opts[p] = set()
+        if p.islower() and p not in ('start', 'end'): opts['small'].add(p)
+        if p.islower() and p not in ('start', 'end'): opts['small'].add(p)
+    opts[p1].add(p2)
+    opts[p2].add(p1)    
+
+def paths(p1, l, twice=''):
+    p = deepcopy(p1)
+    p.append(l)
+    if p.count(twice) > 1: twice = ''
+    if l == 'end':
+        pths.add(tuple(p))
+        return
+    for n in opts[l]:
+        if not ((n != twice and n in p and n in opts['small']) or n == 'start'):
+            paths(p, n, twice)
+
+if __name__ == '__main__':
+    lines = open(sys.argv[1]).read().strip('\n\n').split('\n') # or split \n\n or sth similar
+    
+    opts = {'start': set(), 'end': set(), 'small': set()}
+    [parse(i) for i in lines]
+
+    # challenge 1
+    pths = set()
+    paths([], 'start')
+
+    res1 = str(len(pths))
+    print("challenge 1:" +"\n" +  res1 + "\n")
+
+    # challenge 2
+    pths = set()
+    [paths([], 'start', t) for t in opts['small']]
+
+    res2 = str(len(pths))
+    print("challenge 2:" +"\n" +  res2 + "\n")
+