Start with 2021

2021/d3.py

@@ -0,0 +1,56 @@
+from lib import get_data
+from lib import ints
+from collections import defaultdict
+
+data = get_data(__file__)
+
+
+def count_one_zero(xs, index):
+    ones, zeros = 0, 0
+    for x in xs:
+        if x[index] == "1":
+            ones += 1
+        elif x[index] == "0":
+            zeros += 1
+        else:
+            assert False
+    return (ones, zeros)
+
+
+a = ""
+b = ""
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    if ones > zeros:
+        a += "1"
+        b += "0"
+    elif zeros > ones:
+        a += "0"
+        b += "1"
+    else:
+        assert False
+a, b = int(a, 2), int(b, 2)
+print(a * b)
+
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    c = "1" if ones >= zeros else "0"
+    lines = [l for l in lines if l[i] == c]
+    if len(lines) == 1:
+        break
+(line,) = lines
+a = int(line, 2)
+
+lines = list(data.strip().splitlines())
+for i in range(len(lines[0])):
+    ones, zeros = count_one_zero(lines, i)
+    c = "0" if zeros <= ones else "1"
+    lines = [l for l in lines if l[i] == c]
+    if len(lines) == 1:
+        break
+
+(line,) = lines
+b = int(line, 2)
+print(a * b)