#690677 (Rust) No.1621 Sequence Inversions

• 問題: No.1621 Sequence Inversions
• ユーザー: koba-e964
• 提出日時: 2021-08-18 12:56:29
• 言語: Rust (1.83.0 + proconio)
• 結果: AC
• 実行時間: 402 ms / 3,000 ms
• コード長: 4,693 bytes
• コンパイル時間: 14,151 ms
• コンパイル使用メモリ: 377,640 KB
• 実行使用メモリ: 396,928 KB
• 最終ジャッジ日時: 2024-10-11 12:52:11
• 合計ジャッジ時間: 21,036 ms
• ジャッジサーバーID （参考情報）: judge3 / judge2

ファイルパターン	結果
sample	AC * 3
other	AC * 26

ソースコード

use std::cmp::*;
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes.by_ref().map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr,) => {};
    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };
    ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error"));
}

/// Verified by https://atcoder.jp/contests/abc198/submissions/21774342
mod mod_int {
    use std::ops::*;
    pub trait Mod: Copy { fn m() -> i64; }
    #[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
    pub struct ModInt<M> { pub x: i64, phantom: ::std::marker::PhantomData<M> }
    impl<M: Mod> ModInt<M> {
        // x >= 0
        pub fn new(x: i64) -> Self { ModInt::new_internal(x % M::m()) }
        fn new_internal(x: i64) -> Self {
            ModInt { x: x, phantom: ::std::marker::PhantomData }
        }
    }
    impl<M: Mod, T: Into<ModInt<M>>> Add<T> for ModInt<M> {
        type Output = Self;
        fn add(self, other: T) -> Self {
            let other = other.into();
            let mut sum = self.x + other.x;
            if sum >= M::m() { sum -= M::m(); }
            ModInt::new_internal(sum)
        }
    }
    impl<M: Mod, T: Into<ModInt<M>>> Sub<T> for ModInt<M> {
        type Output = Self;
        fn sub(self, other: T) -> Self {
            let other = other.into();
            let mut sum = self.x - other.x;
            if sum < 0 { sum += M::m(); }
            ModInt::new_internal(sum)
        }
    }
    impl<M: Mod, T: Into<ModInt<M>>> Mul<T> for ModInt<M> {
        type Output = Self;
        fn mul(self, other: T) -> Self { ModInt::new(self.x * other.into().x % M::m()) }
    }
    impl<M: Mod, T: Into<ModInt<M>>> AddAssign<T> for ModInt<M> {
        fn add_assign(&mut self, other: T) { *self = *self + other; }
    }
    impl<M: Mod, T: Into<ModInt<M>>> SubAssign<T> for ModInt<M> {
        fn sub_assign(&mut self, other: T) { *self = *self - other; }
    }
    impl<M: Mod, T: Into<ModInt<M>>> MulAssign<T> for ModInt<M> {
        fn mul_assign(&mut self, other: T) { *self = *self * other; }
    }
    impl<M: Mod> Neg for ModInt<M> {
        type Output = Self;
        fn neg(self) -> Self { ModInt::new(0) - self }
    }
    impl<M> ::std::fmt::Display for ModInt<M> {
        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
            self.x.fmt(f)
        }
    }
    impl<M: Mod> From<i64> for ModInt<M> {
        fn from(x: i64) -> Self { Self::new(x) }
    }
} // mod mod_int

macro_rules! define_mod {
    ($struct_name: ident, $modulo: expr) => {
        #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
        struct $struct_name {}
        impl mod_int::Mod for $struct_name { fn m() -> i64 { $modulo } }
    }
}
const MOD: i64 = 998_244_353;
define_mod!(P, MOD);
type MInt = mod_int::ModInt<P>;

// Tags: partition-number, dp, inversions
fn main() {
    input! {
        n: usize, k: usize,
        a: [i64; n],
    }
    let mut coo = a.clone();
    coo.sort(); coo.dedup();
    let m = coo.len();
    let mut f = vec![0; m];
    for a in a {
        f[coo.binary_search(&a).unwrap()] += 1;
    }
    let lim = n * (n - 1) / 2 + 1;
    let mut help = vec![vec![vec![MInt::new(0); lim]; n + 1]; n + 1];
    for x in 0..n + 1 {
        help[x][0][0] += 1;
        for y in 1..n - x + 1 {
            for i in 0..x * y + 1 {
                let mut me = help[x][y - 1][i];
                if x >= 1 && i >= y {
                    me += help[x - 1][y][i - y];
                }
                help[x][y][i] = me;
            }
        }
    }
    let mut dp = vec![MInt::new(0); lim];
    dp[0] = 1.into();
    let mut x = 0;
    for y in f {
        let mut tmp = vec![MInt::new(0); x * y + 1];
        for i in 0..x * y + 1 {
            tmp[i] = help[x][y][i];
        }
        assert!(tmp[0] == 1.into());
        for j in (0..lim).rev() {
            for u in 1..min(j + 1, tmp.len()) {
                dp[j] = dp[j] + dp[j - u] * tmp[u];
            }
        }
        x += y;
    }
    println!("{}", dp[k]);
}