To solve this problem, we need to determine if a given string is a palindrome. A palindrome reads the same forwards and backwards, but we should ignore non-alphanumeric characters and case differences.

Approach

The approach to solve this problem involves two main steps:

1. Preprocess the String:
   • Remove all non-alphanumeric characters (letters and digits are kept).
   • Convert all characters to lowercase (or uppercase) to ensure case insensitivity.
2. Check Palindrome:
   • Compare the preprocessed string with its reverse. If they are the same, the string is a palindrome.

Solution Code

def is_palindrome(s: str) -> bool:
    # Preprocess the string: keep alphanumeric chars and convert to lowercase
    processed = [c.lower() for c in s if c.isalnum()]
    processed_str = ''.join(processed)
    # Check if the processed string equals its reverse
    return processed_str == processed_str[::-1]

Explanation

1. Preprocessing:
   • We use a list comprehension to iterate over each character in the input string. For each character, we check if it is alphanumeric (c.isalnum()). If it is, we convert it to lowercase (c.lower()).
   • The list of processed characters is then joined into a single string (processed_str).
2. Palindrome Check:
   • The slice processed_str[::-1] reverses the string. We compare this reversed string with the original processed string. If they match, the function returns True (palindrome), else False.

This approach efficiently handles edge cases like empty strings, strings with non-alphanumeric characters, and case differences. It runs in O(n) time complexity (where n is the length of the input string) since each step (preprocessing and reversing) takes linear time. The space complexity is O(n) to store the processed string.

Examples:

• Input: "A man, a plan, a canal: Panama" → Output: True (processed string: "amanaplanacanalpanama").
• Input: "racecar" → Output: True.
• Input: "hello" → Output: False.
• Input: "0P" → Output: False (processed string: "0p" vs reversed "p0").

This solution is optimal and aligns with the requirements of the problem. It is clean, readable, and handles all test cases correctly.

作者声明:本文包含人工智能生成内容。