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Given string str, How do you find the longest palindromic substring in str in Rust

Rust

fn main() {
    let s = "babad";
    println!("{}", longest_palindrome(s));
}

fn longest_palindrome(s: &str) -> String {
    let mut max_len = 0;
    let mut start = 0;

for i in 0..s.len() {
        let len1 = expand_around_center(s, i, i); // odd length palindromes. e.g. "aba" has a center of 'b' and expands to the left and right by 1 each time. 
        let len2 = expand_around_center(s, i, i + 1); // even length palindromes. e.g. "abba" has a center of 'bb' and expands to the left and right by 1 each time.

if len1 > max_len { // if the current palindrome is longer than the previous one... 
            max_len = len1; // ...update the max length... 
            start = i - (max_len - 1) / 2; // ...and update the starting index of the substring that contains it (the substring is always centered around the palindrome).

} else if len2 > max_len { // same as above but for even length palindromes... 
            max_len = len2; 
            start = i - (max_len / 2) + 1;

} else {} // do nothing if neither of these conditions are met (i.e., if neither of these two palindromes are longer than the previous one).

}

return s[start..start + max_len].to_string(); // return a string slice containing only the longest palindrome found in s[..].

fn expand_around_center(s: &str, left: usize, right: usize) -> usize { // this function takes in a string slice and two indices into that slice as arguments...

while left >= 0 && right < s.len() && s[left] == s[right] { // ...and then checks whether or not those indices are valid indices into that slice...

left -= 1; // ...if they are valid indices into that slice, then it decrements left by one and increments right by one...  
            right += 1;

}

return right - left - 1; // ...and returns an integer representing how many characters were checked before either of those indices became invalid or before they stopped being equal to each other (i.e., how long this particular palindrome is).

}    
}

🤖 Code Explanation

This code is written in Rust and it finds the longest palindrome in a given string.

AI coding assistant for busy programmers

Given string str, How do you find the longest palindromic substring in str in Rust

Rust

🤖 Code Explanation

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