Monistus

use std::io::stdin;
use std::convert::TryInto;

fn main() {
    let mut input = stdin().lines();

    let text = input.next().unwrap().unwrap();
    let mut char_stack: Vec<char> = text.chars().rev().collect();
    let mut output = String::new();

    while let Some(character) = char_stack.pop() {
        match character.to_digit(10) {
            Some(digit) => {
                let to_duplicate: Vec<char> = char_stack
                    .iter()
                    .rev()
                    .take(digit.try_into().unwrap())
                    .copied()
                    .collect();

                char_stack.extend(to_duplicate.iter().rev());
            },
            None => {
                output.push(character);
            }
        }
    }

    println!("{output}");
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED