day12: defaultdicts ... TIL

day12.py

@@ -1,19 +1,13 @@
+from collections import defaultdict
 from tools.aoc import AOCDay
 from typing import Any, Dict, List
 
 
 def getCaveMap(lines: List[List[str]]) -> Dict[str, List[str]]:
-    m = {}
-    for l in lines:
-        if l[0] in m:
-            m[l[0]].append(l[1])
-        else:
-            m[l[0]] = [l[1]]
-
-        if l[1] in m:
-            m[l[1]].append(l[0])
-        else:
-            m[l[1]] = [l[0]]
+    m = defaultdict(list)
+    for l, r in lines:
+        m[l].append(r)
+        m[r].append(l)
 
     return m