use std::io::Read; fn get_word() -> String { let stdin = std::io::stdin(); let mut stdin=stdin.lock(); let mut u8b: [u8; 1] = [0]; loop { let mut buf: Vec = Vec::with_capacity(16); loop { let res = stdin.read(&mut u8b); if res.unwrap_or(0) == 0 || u8b[0] <= b' ' { break; } else { buf.push(u8b[0]); } } if buf.len() >= 1 { let ret = String::from_utf8(buf).unwrap(); return ret; } } } fn get() -> T { get_word().parse().ok().unwrap() } // https://yukicoder.me/problems/no/2846 (3) // irb(main):009> [24,22,21,20,18,16,15,14,13,12,11,10,9,8,7,6,5].reduce{|a,b|a.lcm(b)} // => 720720 // 素数 23, 19, 17 だけ特別扱いして、あとは幅 720720 の DP で解く。 fn main() { let k: usize = get(); let n: usize = get(); const W: usize = 720_720; let prs = [23, 19, 17]; let mut dp = vec![0i64; W + 1]; dp[0] = 1; for _ in 0..k { let mut ep = vec![0; W + 1]; for i in 1..n + 1 { if W % i != 0 { continue; } let x = W / i; for j in x..W + 1 { ep[j] += dp[j - x]; } } dp = ep; } let mut ans = dp[W]; for &p in &prs { if k == p { ans += 1; } } println!("{}", ans); }