day 3

1 files changed, 39 insertions, 0 deletions

diff --git a/3.py b/3.py
new file mode 100644
index 0000000..990c9ef
--- /dev/null
+++ b/3.py
@@ -0,0 +1,39 @@
+import re
+from collections import defaultdict
+from collections.abc import Iterator
+from functools import reduce
+from operator import mul
+from sys import stdin
+
+num_re = re.compile("[0-9]+")
+
+inp = [line.rstrip() for line in stdin]
+
+
+def find_adjacent_symbols(
+    inp: list[str], ly: int, sx: int, ex: int
+) -> Iterator[tuple[int, int]]:
+    for x in range(max(0, sx - 1), min(ex + 1, len(l))):
+        for y in range(max(0, ly - 1), min(ly + 2, len(inp))):
+            if y == ly and sx <= x < ex:
+                continue
+            if inp[y][x] != "." and not inp[y][x].isdigit():
+                yield x, y
+
+
+p1 = 0
+p2_gears: defaultdict[tuple[int, int], list[int]] = defaultdict(list)
+for ly, l in enumerate(inp):
+    for match in num_re.finditer(l):
+        value = int(match.group())
+        sx, ex = match.span()
+        is_part_no = False
+        for x, y in find_adjacent_symbols(inp, ly, sx, ex):
+            if inp[y][x] == "*":
+                p2_gears[x, y].append(value)
+            is_part_no = True
+        if is_part_no:
+            p1 += value
+
+print(p1)
+print(sum(reduce(mul, nums) for nums in p2_gears.values() if len(nums) > 1))