2025(02): solve part 2

Grafpuzzels zijn het soms.

2025/02/README.md

@@ -41,3 +41,27 @@ Your job is to find all of the invalid IDs that appear in the given ranges. In t
 Adding up all the invalid IDs in this example produces _`1227775554`_.
 
 _What do you get if you add up all of the invalid IDs?_
+
+### Part Two
+
+The clerk quickly discovers that there are still invalid IDs in the ranges in your list. Maybe the young Elf was doing other silly patterns as well?
+
+Now, an ID is invalid if it is made only of some sequence of digits repeated _at least_ twice. So, `12341234` (`1234` two times), `123123123` (`123` three times), `1212121212` (`12` five times), and `1111111` (`1` seven times) are all invalid IDs.
+
+From the same example as before:
+
+*   `11-22` still has two invalid IDs, _`11`_ and _`22`_.
+*   `95-115` now has two invalid IDs, _`99`_ and _`111`_.
+*   `998-1012` now has two invalid IDs, _`999`_ and _`1010`_.
+*   `1188511880-1188511890` still has one invalid ID, _`1188511885`_.
+*   `222220-222224` still has one invalid ID, _`222222`_.
+*   `1698522-1698528` still contains no invalid IDs.
+*   `446443-446449` still has one invalid ID, _`446446`_.
+*   `38593856-38593862` still has one invalid ID, _`38593859`_.
+*   `565653-565659` now has one invalid ID, _`565656`_.
+*   `824824821-824824827` now has one invalid ID, _`824824824`_.
+*   `2121212118-2121212124` now has one invalid ID, _`2121212121`_.
+
+Adding up all the invalid IDs in this example produces _`4174379265`_.
+
+_What do you get if you add up all of the invalid IDs using these new rules?_

2025/02/part2.py

@@ -0,0 +1,64 @@
+def is_invalid_id(num):
+	# print("Testing", num)
+	num_str = str(num)
+	num_len = len(num_str)
+	for period in range(1, num_len):
+		# print("period =", period)
+		# Period should be a factor of num_len
+		if num_len % period != 0:
+			continue
+
+		# Start with True, make False when it fails
+		palin = True
+		for idx in range(period, num_len, period):
+			# print("idx =", idx)
+			# print(num_str[:period], "=?=", num_str[idx:idx + period])
+			if num_str[:period] != num_str[idx:idx + period]:
+				# print(False)
+				palin = False
+				# print(False)
+		if palin:
+			# print("Returning palin")
+			return True
+	
+	# No period has yielded repetition:
+	return False
+			
+if __name__ == "__main__":
+	with open("input", "r") as fp:
+		rangestrs = fp.read().split(",")
+		ranges = []
+		for rangestr in rangestrs:
+			a, b = rangestr.split("-")
+			a_int, b_int = int(a), int(b)
+			ranges.append((a, b))
+			assert a_int < b_int, f"Range invalid: {a} is not smaller than {b}"
+
+		illegal_counter = 0
+		illegal_sum = 0
+		for a, b in ranges:
+			a_int, b_int = int(a), int(b)
+			for num in range(a_int, b_int + 1):
+				if is_invalid_id(num):
+					print(num, "is a palindrome thing")
+					illegal_counter += 1
+					illegal_sum += num
+				# num_str = str(num)
+				# num_len = len(num_str)
+				# palin = False
+				# # Look at the different options for lengths
+				# for partlen in range(2, num_len + 1):
+				# 	# Only continue if it's a factor
+				# 	if num_len % partlen != 0:
+				# 		continue
+				# 	for idx in range(partlen, num_len, partlen): 
+				# 		if num_str[:partlen] == num_str[idx:idx + partlen]:
+				# 			continue
+				# 		palin = True
+				# 		break
+				# if palin:
+				# 	print(num_str, "is a palindrome thing")
+				# 	illegal_counter += 1
+				# 	illegal_sum += num
+
+		print(illegal_counter, illegal_sum)