#344877 (Rust) No.827 総神童数

• 問題: No.827 総神童数
• ユーザー: koba-e964
• 提出日時: 2019-05-03 23:06:03
• 言語: Rust (1.77.0 + proconio)
• 結果: AC
• 実行時間: 124 ms / 2,000 ms
• コード長: 6,038 bytes
• コンパイル時間: 14,937 ms
• コンパイル使用メモリ: 392,308 KB
• 実行使用メモリ: 44,980 KB
• 最終ジャッジ日時: 2024-06-10 07:05:47
• 合計ジャッジ時間: 16,532 ms
• ジャッジサーバーID （参考情報）: judge2 / judge4

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	1 ms; 6,812 KB
testcase_01	AC	2 ms; 6,812 KB
testcase_02	AC	2 ms; 6,812 KB
testcase_03	AC	1 ms; 6,816 KB
testcase_04	AC	2 ms; 6,940 KB
testcase_05	AC	1 ms; 6,940 KB
testcase_06	AC	1 ms; 6,944 KB
testcase_07	AC	2 ms; 6,940 KB
testcase_08	AC	2 ms; 6,940 KB
testcase_09	AC	124 ms; 44,980 KB
testcase_10	AC	29 ms; 15,932 KB
testcase_11	AC	2 ms; 6,940 KB
testcase_12	AC	12 ms; 8,976 KB
testcase_13	AC	71 ms; 37,812 KB
testcase_14	AC	4 ms; 6,940 KB
testcase_15	AC	27 ms; 16,364 KB
testcase_16	AC	74 ms; 29,520 KB
testcase_17	AC	94 ms; 35,704 KB
testcase_18	AC	38 ms; 20,104 KB
testcase_19	AC	109 ms; 21,848 KB
testcase_20	AC	72 ms; 16,532 KB
testcase_21	AC	48 ms; 12,668 KB
testcase_22	AC	81 ms; 17,920 KB
testcase_23	AC	1 ms; 6,940 KB
testcase_24	AC	92 ms; 19,636 KB
testcase_25	AC	64 ms; 15,360 KB
testcase_26	AC	94 ms; 19,624 KB
testcase_27	AC	55 ms; 13,792 KB
testcase_28	AC	55 ms; 13,696 KB
testcase_29	AC	39 ms; 11,264 KB
testcase_30	AC	12 ms; 6,940 KB
testcase_31	AC	31 ms; 9,216 KB
testcase_32	AC	29 ms; 8,960 KB
testcase_33	AC	105 ms; 21,204 KB
testcase_34	AC	96 ms; 19,628 KB
testcase_35	AC	30 ms; 9,344 KB
testcase_36	AC	50 ms; 12,404 KB
testcase_37	AC	64 ms; 15,400 KB
testcase_38	AC	105 ms; 21,008 KB

ソースコード

#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
use std::io::{Write, BufWriter};
// 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),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, [ $t:tt ]) => {{
        let len = read_value!($next, usize);
        (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/arc093/submissions/3968098
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 }
        }
        pub fn pow(self, mut e: i64) -> Self {
            debug_assert!(e >= 0);
            let mut sum = ModInt::new_internal(1);
            let mut cur = self;
            while e > 0 {
                if e % 2 != 0 { sum *= cur; }
                cur *= cur;
                e /= 2;
            }
            sum
        }
        #[allow(dead_code)]
        pub fn inv(self) -> Self { self.pow(M::m() - 2) }
    }
    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> ::std::fmt::Debug 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 = 1_000_000_007;
define_mod!(P, MOD);
type ModInt = mod_int::ModInt<P>;

// Depends on ModInt.rs
fn fact_init(w: usize) -> (Vec<ModInt>, Vec<ModInt>) {
    let mut fac = vec![ModInt::new(1); w];
    let mut invfac = vec![0.into(); w];
    for i in 1 .. w {
        fac[i] = fac[i - 1] * i as i64;
    }
    invfac[w - 1] = fac[w - 1].inv();
    for i in (0 .. w - 1).rev() {
        invfac[i] = invfac[i + 1] * (i as i64 + 1);
    }
    (fac, invfac)
}

fn dfs(v: usize, par: usize, g: &[Vec<usize>], fac: &[ModInt], invfac: &[ModInt],
       d: usize) -> ModInt {
    let mut sum = fac[g.len()] * invfac[d + 1] * fac[d];
    for &w in &g[v] {
        if w == par { continue; }
        sum += dfs(w, v, g, fac, invfac, d + 1);
    }
    sum
}

fn solve() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }
    input! {
        n: usize,
        uv: [(usize1, usize1); n - 1],
    }
    let (fac, invfac) = fact_init(n + 1);
    let mut g = vec![vec![]; n];
    for &(u, v) in &uv {
        g[u].push(v);
        g[v].push(u);
    }
    let ans = dfs(0, n, &g, &fac, &invfac, 0);
    puts!("{}\n", ans);
}

fn main() {
    // In order to avoid potential stack overflow, spawn a new thread.
    let stack_size = 104_857_600; // 100 MB
    let thd = std::thread::Builder::new().stack_size(stack_size);
    thd.spawn(|| solve()).unwrap().join().unwrap();
}