2024 day 3.

src/holt59/aoc/2024/day3.py

@@ -1,10 +1,36 @@
+import re
 import sys
+from typing import Iterator
 
-lines = sys.stdin.read().splitlines()
 
-answer_1 = ...
+def extract_multiply(line: str) -> Iterator[int]:
+    for m in re.findall(r"mul\(([0-9]{1,3}),\s*([0-9]{1,3})\)", line):
+        yield int(m[0]) * int(m[1])
 
-answer_2 = ...
+
+def remove_disabled_parts(line: str) -> str:
+    fixed_line, accumulate = "", True
+    while line:
+        if accumulate:
+            if (dont_i := line.find("don't()")) != -1:
+                fixed_line += line[:dont_i]
+                line, accumulate = line[dont_i:], False
+            else:
+                fixed_line += line
+                line = ""
+        else:
+            if (do_i := line.find("do()")) != -1:
+                line, accumulate = line[do_i:], True
+            else:
+                line = ""
+
+    return fixed_line
+
+
+line = sys.stdin.read().strip()
+
+answer_1 = sum(extract_multiply(line))
+answer_2 = sum(extract_multiply(remove_disabled_parts(line)))
 
 print(f"answer 1 is {answer_1}")
 print(f"answer 2 is {answer_2}")