125. Valid Palindrome

Problem Statement

A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.

Given a string s, return true if it is a palindrome, or false otherwise.

Example 1:

Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.

Example 2:

Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.

Example 3:

Input: s = " "
Output: true
Explanation: s is an empty string "" after removing non-alphanumeric characters.
Since an empty string reads the same forward and backward, it is a palindrome.

Constraints:

1 <= s.length <= 2 * 10⁵
s consists only of printable ASCII characters.

Solution:

Rust

impl Solution {
    pub fn is_palindrome(s: String) -> bool {
        let chars: Vec<char> = s
            .chars()
            .filter_map(|c| {
                if c.is_alphanumeric() {
                    Some(c.to_ascii_lowercase())
                } else {
                    None
                }
            })
            .collect();

        if chars.len() == 0 {
            return true;
        }

        let (mut i, mut j) = (0, chars.len() - 1);
        while i < j {
            if chars[i] != chars[j] {
                return false;
            }
            i += 1;
            j -= 1;
        }

        true
    }
}

125. Valid Palindrome #

Problem Statement #

Solution: #

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125. Valid Palindrome

Problem Statement

Solution:

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