Palindromi

use std::{io::stdin};

fn main() {
    let stdin = stdin();
    let (n, k): (usize, usize) = {
        let mut s = String::new();
        stdin.read_line(&mut s).unwrap();
        let mut l = s.trim_end().split_whitespace();
        (l.next().unwrap().parse().unwrap(), l.next().unwrap().parse().unwrap())
    };

    let letters: Vec<char> = "abcdefghijklmnopqrstuvwxyz".chars().collect();

    let mut palindromi = String::with_capacity(n);

    for i in 0..(k/2) {
        palindromi.insert(i, letters[i % letters.len()]);
        palindromi.insert(palindromi.len() - 1 - i, letters[i % letters.len()]);
    }
    if k % 2 != 0 {
        palindromi.insert(k / 2, letters[(k / 2 + 1) % letters.len()]);
    }
    
    let mut fill = String::with_capacity(n - k);
    for i in 0..((n - k) / 2) {
        fill.push(letters[i % letters.len()]);
    }

    println!("{}", fill.clone() + &*palindromi + &*fill + if (n - k) % 2 != 0 {"z"} else {""})
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED