LeetCode Python Solutions: 125. Valid Palindrome #python #coding #datastructures #leetcode смотреть онлайн

ZeroStress LeetCode Python Solutions: 125. Valid Palindrome Problem #python #leetcode

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Important Concepts:
1. Palindrome: A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward.
2. Alphanumeric characters: Alphanumeric characters are characters that are either letters or digits.
3. Character case: In this problem, we are required to ignore character case, i.e., uppercase and lowercase characters are considered equal.
4. Time complexity: Time complexity refers to the amount of time taken by an algorithm to run as a function of the input size. It is usually expressed in big O notation.
5. Space complexity: Space complexity refers to the amount of memory used by an algorithm to run as a function of the input size. It is usually expressed in big O notation.

This solution has a time complexity of O(n), where n is the length of the input string. The filter() method removes all non-alphanumericcharacters from the string in linear time. Then, comparing the resulting string to its reverse takes linear time as well, resulting in a total time complexity of O(n).
The space complexity of this solution is also O(n), as we create a new string to store the filtered input string, which can be as large as the original input string.

Overall, this solution is both time and space efficient, making it an optimal solution for the "Valid Palindrome" problem.

The problem is asking us to determine if a given string is a palindrome, which means that it reads the same forward and backward. In order to solve this problem, we can use a two-step approach:
Step 1: Preprocessing
• First, we need to preprocess the input string by removing all non-alphanumeric characters and converting it to lowercase.
• We can achieve this by using the lower(), filter(), and join() methods in Python. The lower() method converts the string to lowercase, while the filter() method removes all non-alphanumeric characters, and the join() method concatenates the remaining characters back into a single string.
Step 2: Checking for Palindrome
• Next, we need to check if the resulting string is a palindrome.
• We can do this by comparing the string to its reverse.
• We can obtain the reverse of a string using Python's slicing syntax s[::-1].
• If the reversed string is equal to the original string, then the input string is a palindrome and we can return True. Otherwise, we return False.
The approach used in this solution is to preprocess the input string to simplify the problem of checking for a palindrome. Then, by comparing the string to its reverse, we can determine if the string is a palindrome in a straightforward and efficient way.