Problem:
Score : 200 points

Problem Statement

Given are 1-digit positive integers a and b. Consider these two strings: the concatenation of b copies of the digit a, and the concatenation of a copies of the digit b. Which of these is lexicographically smaller?

Constraints

1 \leq a \leq 9

1 \leq b \leq 9

a and b are integers.

Input

Input is given from Standard Input in the following format:

a b

Output

Print the lexicographically smaller of the two strings. (If the two strings are equal, print one of them.)

Sample Input 1

4 3

Sample Output 1

3333

We have two strings 444 and 3333. Between them, 3333 is the lexicographically smaller.

Sample Input 2

7 7

Sample Output 2

7777777

Solution in Rust (1.42.0) (judge verdict: Accepted)

#![allow(unused_imports)]
#![allow(unused_macros)]
// use proconio::input;
use std::cmp::{Ordering::*, Reverse};
use std::collections::{BTreeMap, BTreeSet};
use std::io::{self, BufWriter, Write};
use std::str::{self, SplitAsciiWhitespace};

// I have no idea what I'm doing

macro_rules! answer {
    ($out:ident, $ans:expr) => {
        writeln!($out, "{}", $ans)
    };
}

fn main() -> Result<(), io::Error> {
    let (stdin, stdout) = (io::stdin(), io::stdout());
    let mut scan = UnsafeScanner::new(stdin.lock());
    let mut out = BufWriter::new(stdout.lock());

    let a: usize = scan.token();
    let b: usize = scan.token();

    let sa = (0..b).map(|_| a as u8 + b'0').map(|x| x as char).collect::<String>();
    let sb = (0..a).map(|_| b as u8 + b'0').map(|x| x as char).collect::<String>();

    answer!(out, if sa < sb { sa } else { sb })
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Mostly copied from https://github.com/EbTech/rust-algorithms/blob/master/src/scanner.rs
/// Same API as Scanner but nearly twice as fast, using horribly unsafe dark arts
/// **REQUIRES** Rust 1.34 or higher
pub struct UnsafeScanner<R> {
    reader: R,
    buf_str: Vec<u8>,
    buf_iter: SplitAsciiWhitespace<'static>,
}

impl<R: io::BufRead> UnsafeScanner<R> {
    pub fn new(reader: R) -> Self {
        Self {
            reader,
            buf_str: vec![],
            buf_iter: "".split_ascii_whitespace(),
        }
    }

    /// This function should be marked unsafe, but noone has time for that in a
    /// programming contest. Use at your own risk!
    pub fn token<T: str::FromStr>(&mut self) -> T {
        loop {
            if let Some(token) = self.buf_iter.next() {
                return token.parse().ok().expect("Failed parse [Scanner]");
            }
            self.buf_str.clear();
            self.reader
                .read_until(b'\n', &mut self.buf_str)
                .expect("Failed read");
            self.buf_iter = unsafe {
                let slice = str::from_utf8_unchecked(&self.buf_str);
                std::mem::transmute(slice.split_ascii_whitespace())
            }
        }
    }

    pub fn pair<T: str::FromStr>(&mut self) -> (T, T) {
        (self.token(), self.token())
    }
}

// aka #![feature(bool_to_option)]
trait BoolThen {
    fn then_<T>(self, f: impl FnOnce() -> T) -> Option<T>;
}

impl BoolThen for bool {
    fn then_<T>(self, f: impl FnOnce() -> T) -> Option<T> {
        if self {
            Some(f())
        } else {
            None
        }
    }
}

trait BoolToYes {
    fn yes(self) -> &'static str;
}

impl BoolToYes for bool {
    fn yes(self) -> &'static str {
        match self {
            true => "Yes",
            false => "No",
        }
    }
}