I want to solve the following problem: Given a string n representing an integer, return the closest integer (not including itself), which is a palindrome. If there is a tie, return the smaller one. The closest is defined as the absolute difference minimized between two integers. Here is what I have tried: def nearestPalindromic(n: str) -> str: # Convert input string n to integer original_n = int(n) # Calculate the length of the number as a string str_n = str(original_n) length = len(str_n) # Special case: single digit numbers if length == 1: return str(original_n) # Create the base palindrome by mirroring the left half left_half = str_n[length + 1) // 2] # Left half including middle if odd mirrored = int(left_half + left_half[-(length // 2):][::-1]) # Create candidates by modifying the left half left_num = int(left_half) lower_half = str(left_num - 1) # Decrease left half upper_half = str(left_num + 1) # Increase left half lower_pal = int(lower_half + lower_half[-(length // 2):][::-1]) upper_pal = int(upper_half + upper_half[-(length // 2):][::-1]) # Handle edge cases like 1000 -> 999, or 9999 -> 10001 edge_case = 10 ** (length - 1) - 1 # 999 for 1000 large_case = 10 ** length + 1 # 10001 for 9999 # List of all candidates candidates = [mirrored, lower_pal, upper_pal, edge_case, large_case] # Exclude the original number from candidates candidates = [c for c in candidates if c != original_n] # Find the closest palindrome using the key that compares by absolute difference first, # and by value second for ties closest = min(candidates, key=lambda x: (abs(x - original_n), x)) # Return the result as a string return str(closest) but I get this error: Input n = "123" Output 122 Expected "121" Continue reading...
