Day 03 (glamorized)

day03/part2.py

@@ -1,20 +1,18 @@
 #!/usr/bin/env python3
+from collections import Counter
 
 
 def find(is_lowest):
-    lines = (x.strip() for x in open("input.txt"))
+    lines = [x.strip() for x in open("input.txt")]
     for bit in range(12):
-        zeros = []
-        ones = []
-        for line in lines:
-            zeros.append(line) if line[bit] == '0' else ones.append(line)
-        lines = zeros if (len(zeros) > len(ones)) != is_lowest else ones
-        if len(lines) <= 1:
-            break
-    return lines[0]
+        common = (max if is_lowest else min)(
+            map(lambda x: x[::-1], Counter(s[bit] for s in lines).items())
+        )[1]
+        lines = [s for s in lines if s[bit] == common]
+    return lines
 
 
-gamma = int(''.join(find(True)), 2)
-epsilon = int(''.join(find(False)), 2)
+gamma = int(''.join(find(False)), 2)
+epsilon = int(''.join(find(True)), 2)
 
 print(gamma * epsilon)