day 3 alt

3/b_better.py

@@ -0,0 +1,38 @@
+width = 12
+
+with open("input.txt") as f:
+    lines = [int(i.strip(), 2) for i in f.readlines()]
+
+
+def count_digits(ar, pos):
+    zeros = 0
+    ones = 0
+
+    for num in ar:
+        if num & (1 << (width - pos - 1)):
+            ones += 1
+        else:
+            zeros += 1
+
+    return zeros, ones
+
+
+def filter_by_digit(lines, position, value):
+    return [i for i in lines if int(bool(i & (1 << (width - position - 1)))) == value]
+
+
+def filter_by(nums, func):
+    position = 0
+    while len(nums) > 1:
+        zeros, ones = count_digits(nums, position)
+        digit = func(zeros, ones)
+        nums = filter_by_digit(nums, position, digit)
+        position += 1
+
+    return nums[0]
+
+
+oxy = filter_by(lines, lambda zeros, ones: 1 if ones >= zeros else 0)
+co2 = filter_by(lines, lambda zeros, ones: 1 if ones < zeros else 0)
+
+print(oxy * co2)