Valid palindrome

Two Pointers String

52.8% acceptance

Jan 12, 2026

11470

8633

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.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn is_palindrome(s: String) -> bool {
    let chars: Vec<char> = s.chars()
      .filter(|c| c.is_alphanumeric())
      .map(|c| c.to_ascii_lowercase())
      .collect();
    
    let mut left = 0;
    let mut right = chars.len();
    
    while left < right {
      right -= 1;
      if chars[left] != chars[right] {
        return false;
      }
      left += 1;
    }
    
    true
  }
}