Day 2: Part 1

day2/main.py

@@ -0,0 +1,20 @@
+def is_invalid_id(n: int) -> bool:
+    s = str(n)
+    if len(s) % 2 != 0:
+        return False
+    half = len(s) // 2
+    return s[:half] == s[half:]
+
+
+total = 0
+
+with open("input.txt") as f:
+    line = f.read().strip()
+
+for part in line.split(","):
+    lo, hi = map(int, part.split("-"))
+    for n in range(lo, hi + 1):
+        if is_invalid_id(n):
+            total += n
+
+print(total)