use std::io::stdin; struct Problem { n: usize, k: usize, xs: Vec, } impl Problem { fn read(mut r: R) -> Problem { let (n, k) = r.read_usize_2(); let xs = r.read_vec_any(); Problem { n, k, xs } } fn solve(&self) -> Answer { let comb = combinations(self.n, self.k); let ans = comb.iter().filter(|bs|{ let sum = self.xs.iter().zip(bs.iter()).map(|(x, b)| x * b).sum::(); let sum_998244353 = sum % 998244353; let sum_998 = sum % 998; sum_998244353 <= sum_998 }).count() as i64; let ans = ans % 998; Answer { ans } } } fn combinations(n: usize, k: usize) -> Vec> { let mut ret = Vec::new(); // 0 を n-k 個, 1をk個並べる let mut seq01 = std::iter::repeat(0).take(n - k).chain(std::iter::repeat(1).take(k)).collect::>(); while{ ret.push(seq01.clone()); next_permutation(&mut seq01) }{}; ret } // https://ngtkana.hatenablog.com/entry/2021/11/08/000209 pub fn next_permutation(a: &mut [T]) -> bool { if a.is_empty() { return false; } let Some(i) = (0..a.len() - 1).rfind(|&i| a[i] < a[i + 1]) else { return false }; let j = a.iter().rposition(|x| x > &a[i]).unwrap(); a.swap(i, j); a[i + 1..].reverse(); true } #[derive(Clone, Debug, PartialEq, Eq)] struct Answer { ans: i64, } impl Answer { fn print(&self) { println!("{}", self.ans); } } fn main() { Problem::read(ProconReader::new(stdin().lock())).solve().print(); } #[cfg(test)] mod tests { use super::*; #[allow(dead_code)] fn check(input: &str, expected: Answer) { let actual = Problem::read(ProconReader::new(input.as_bytes())).solve(); assert_eq!(expected, actual); } #[test] fn test_problem() { let _input = " 3 4 " .trim(); // check(_input, Answer { ans: 7 }); } } // ====== snippet ====== #[allow(unused_imports)] use myio::*; pub mod myio { use std::io::BufRead; pub trait IProconReader { fn read_line(&mut self) -> String; fn read_bytes(&mut self) -> Vec { self.read_line().as_bytes().to_vec() } fn read_any_1(&mut self) -> T where T: std::str::FromStr, T::Err: std::fmt::Debug, { let buf = self.read_line(); buf.parse::().unwrap() } fn read_any_2(&mut self) -> (T0, T1) where T0: std::str::FromStr, T0::Err: std::fmt::Debug, T1: std::str::FromStr, T1::Err: std::fmt::Debug, { let buf = self.read_line(); let splitted = buf.trim().split(' ').collect::>(); let a0 = splitted[0].parse::().unwrap(); let a1 = splitted[1].parse::().unwrap(); (a0, a1) } fn read_any_3(&mut self) -> (T0, T1, T2) where T0: std::str::FromStr, T0::Err: std::fmt::Debug, T1: std::str::FromStr, T1::Err: std::fmt::Debug, T2: std::str::FromStr, T2::Err: std::fmt::Debug, { let buf = self.read_line(); let splitted = buf.trim().split(' ').collect::>(); let a0 = splitted[0].parse::().unwrap(); let a1 = splitted[1].parse::().unwrap(); let a2 = splitted[2].parse::().unwrap(); (a0, a1, a2) } fn read_any_4(&mut self) -> (T0, T1, T2, T3) where T0: std::str::FromStr, T0::Err: std::fmt::Debug, T1: std::str::FromStr, T1::Err: std::fmt::Debug, T2: std::str::FromStr, T2::Err: std::fmt::Debug, T3: std::str::FromStr, T3::Err: std::fmt::Debug, { let buf = self.read_line(); let splitted = buf.trim().split(' ').collect::>(); let a0 = splitted[0].parse::().unwrap(); let a1 = splitted[1].parse::().unwrap(); let a2 = splitted[2].parse::().unwrap(); let a3 = splitted[3].parse::().unwrap(); (a0, a1, a2, a3) } fn read_vec_any(&mut self) -> Vec where T: std::str::FromStr, T::Err: std::fmt::Debug, { let buf = self.read_line(); buf.trim().split(' ').map(|s| s.parse::().unwrap()).collect::>() } fn read_vec_i64(&mut self) -> Vec { self.read_vec_any::() } fn read_vec_usize(&mut self) -> Vec { self.read_vec_any::() } fn read_vec_str(&mut self) -> Vec { self.read_vec_any::() } fn read_i64_1(&mut self) -> i64 { self.read_any_1::() } fn read_i64_2(&mut self) -> (i64, i64) { self.read_any_2::() } fn read_i64_3(&mut self) -> (i64, i64, i64) { self.read_any_3::() } fn read_i64_4(&mut self) -> (i64, i64, i64, i64) { self.read_any_4::() } fn read_usize_1(&mut self) -> usize { self.read_any_1::() } fn read_usize_2(&mut self) -> (usize, usize) { self.read_any_2::() } fn read_usize_3(&mut self) -> (usize, usize, usize) { self.read_any_3::() } fn read_usize_4(&mut self) -> (usize, usize, usize, usize) { self.read_any_4::() } } pub struct ProconReader { buf_read: R, } impl ProconReader { pub fn new(buf_read: R) -> ProconReader { ProconReader { buf_read } } } impl IProconReader for ProconReader { fn read_line(&mut self) -> String { let mut buffer = String::new(); self.buf_read.read_line(&mut buffer).unwrap(); buffer.trim().to_string() } } }