Only use the symbol '*' in part 2

2023/day03/solutions.py

@@ -7,15 +7,14 @@
     ls = f.read().strip().split("\n")
 
 box = list(itertools.product((-1, 0, 1), (-1, 0, 1)))
-symbols = {
-    (i, j)
+parts_by_symbol = {
+    (i, j): (x, [])
     for i, l in enumerate(ls)
     for j, x in enumerate(l)
     if x != "." and not x.isdigit()
 }
 
 part_sum = 0
-parts_by_symbol = defaultdict(list)
 
 for i, l in enumerate(ls):
     for match in re.finditer(r"\d+", l):
@@ -25,13 +24,19 @@
             for di, dj in box
             for j in range(match.start(), match.end())
         }
-        if symbols & boundary:
+        if parts_by_symbol.keys() & boundary:
             part_sum += n
-        for symbol in symbols & boundary:
-            parts_by_symbol[symbol].append(n)
+        for symbol in parts_by_symbol.keys() & boundary:
+            parts_by_symbol[symbol][1].append(n)
 
 # Part 1
 print(part_sum)
 
 # Part 2
-print(sum(math.prod(v) for v in parts_by_symbol.values() if len(v) == 2))
+print(
+    sum(
+        math.prod(parts)
+        for symbol, parts in parts_by_symbol.values()
+        if len(parts) == 2 and symbol == "*"
+    )
+)