q061.rs

use proconio::{input, fastout};
use std::collections::VecDeque;
const QMAX: usize = 100000;

#[fastout]
fn main() {
  let mut data = VecDeque::with_capacity(QMAX);
  input! { tx: [(usize, usize)], };
  for txi in tx {
    match txi {
      (1, x) => data.push_front(x),
      (2, x) => data.push_back(x),
      (3, x) => println!("{}", data[x-1]),
      _ => unreachable!(),
    }
  }
}