Day 03

day03/part2.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+import re
+
+lines = (x.strip() for x in open("input.txt"))
+
+result = 0
+nums = [dict(), dict(), dict()]
+signals = []
+DIGIT = re.compile("\d+")
+
+
+for idx, line in enumerate(lines):
+    next_num_items = [(idx, match.start(), match.end(), int(line[match.start():match.end()])) for match in DIGIT.finditer(line)]
+    next_num_items = {i: val for val in next_num_items for i in range(val[1], val[2])}
+    next_char_idxs = [j for j, char in enumerate(line) if char in "*"]
+    nums = nums[1:] + [next_num_items]
+
+    # check
+    for signal in signals:
+        found = set()
+        for i in range(signal-1, signal+2):
+            for j in range(0, 3):
+                if i in nums[j]:
+                    found.add(nums[j][i])
+        if len(found) == 2:
+            result += found.pop()[3] * found.pop()[3]
+
+    signals = next_char_idxs
+
+print(result)