q025.rs

use itertools::Itertools;

fn main() {
  proconio::input! { n: i64, b: i64, };
  let mut log10b = 0;
  while 10i64.pow(log10b) <= b { log10b += 1; }
  let log10b = log10b as usize;
  let digits_iter = (0..=9).combinations_with_replacement(log10b);

  let mut ans = 0;
  for digits in digits_iter {
    let f: i64 = digits.iter().product();
    let mut m = b + f;
    if m > n { continue; }
    let mut m_digits = vec![];
    for _ in 0..log10b {
      m_digits.push(m % 10);
      m /= 10;
    }
    m_digits.sort();
    if m_digits == digits { ans += 1; eprintln!("{:?}", digits); }
  }
  println!("{}", ans);
}