結果

問題 No.916 Encounter On A Tree
ユーザー akakimidori
提出日時 2019-10-26 05:31:19
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 6 ms / 2,000 ms
コード長 4,388 bytes
コンパイル時間 12,121 ms
コンパイル使用メモリ 401,796 KB
実行使用メモリ 6,944 KB
最終ジャッジ日時 2024-09-13 20:13:35
合計ジャッジ時間 14,326 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 5
other AC * 56
権限があれば一括ダウンロードができます

ソースコード

diff # 

// ---------- begin ModInt ----------
const MOD: u32 = 1_000_000_007;

#[derive(Clone, Copy)]
struct ModInt(u32);

impl std::ops::Add for ModInt {
    type Output = ModInt;
    fn add(self, rhs: ModInt) -> Self::Output {
        let mut d = self.0 + rhs.0;
        if d >= MOD {
            d -= MOD;
        }
        ModInt(d)
    }
}

impl std::ops::AddAssign for ModInt {
    fn add_assign(&mut self, rhs: ModInt) {
        *self = *self + rhs;
    }
}

impl std::ops::Sub for ModInt {
    type Output = ModInt;
    fn sub(self, rhs: ModInt) -> Self::Output {
        let mut d = self.0 + MOD - rhs.0;
        if d >= MOD {
            d -= MOD;
        }
        ModInt(d)
    }
}

impl std::ops::SubAssign for ModInt {
    fn sub_assign(&mut self, rhs: ModInt) {
        *self = *self - rhs;
    }
}

impl std::ops::Mul for ModInt {
    type Output = ModInt;
    fn mul(self, rhs: ModInt) -> Self::Output {
        ModInt((self.0 as u64 * rhs.0 as u64 % MOD as u64) as u32)
    }
}

impl std::ops::MulAssign for ModInt {
    fn mul_assign(&mut self, rhs: ModInt) {
        *self = *self * rhs;
    }
}

impl std::ops::Neg for ModInt {
    type Output = ModInt;
    fn neg(self) -> Self::Output {
        ModInt(if self.0 == 0 {0} else {MOD - self.0})
    }
}

/* 
impl std::fmt::Display for ModInt {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}
*/

#[allow(dead_code)]
impl ModInt {
    pub fn new(n: u32) -> ModInt {
        ModInt(n % MOD)
    }
    pub fn zero() -> ModInt {
        ModInt(0)
    }
    pub fn one() -> ModInt {
        ModInt(1)
    }
    pub fn pow(self, mut n: u32) -> ModInt {
        let mut t = ModInt::one();
        let mut s = self;
        while n > 0 {
            if n & 1 == 1 {
                t *= s;
            }
            s *= s;
            n >>= 1;
        }
        t
    }
    pub fn inv(self) -> ModInt {
        self.pow(MOD - 2)
    }
}
// ---------- end ModInt ----------
// ---------- begin Precalc ----------
#[allow(dead_code)]
struct Precalc {
    inv: Vec<ModInt>,
    fact: Vec<ModInt>,
    ifact: Vec<ModInt>,
}

#[allow(dead_code)]
impl Precalc {
    pub fn new(n: usize) -> Precalc {
        let mut inv = vec![ModInt::one(); n + 1];
        let mut fact = vec![ModInt::one(); n + 1];
        let mut ifact = vec![ModInt::one(); n + 1];
        for i in 2..(n + 1) {
            inv[i] = -inv[MOD as usize % i] * ModInt(MOD / i as u32);
            fact[i] = fact[i - 1] * ModInt(i as u32);
            ifact[i] = ifact[i - 1] * inv[i];
        }
        Precalc {
            inv: inv,
            fact: fact,
            ifact: ifact,
        }
    }
    pub fn inv(&self, n: usize) -> ModInt {
        self.inv[n]
    }
    pub fn fact(&self, n: usize) -> ModInt {
        self.fact[n]
    }
    pub fn ifact(&self, n: usize) -> ModInt {
        self.ifact[n]
    }
    pub fn comb(&self, n: usize, k: usize) -> ModInt {
        if k > n {
            return ModInt::zero();
        }
        self.fact[n] * self.ifact[k] * self.ifact[n - k]
    }
}
// ---------- end Precalc ----------

use std::cmp::{max, min};

fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let d: usize = it.next().unwrap().parse().unwrap();
    let l: usize = it.next().unwrap().parse().unwrap();
    let r: usize = it.next().unwrap().parse().unwrap();
    let k: usize = it.next().unwrap().parse().unwrap();
    let x = (l + 1).next_power_of_two().trailing_zeros() as usize;
    let y = (r + 1).next_power_of_two().trailing_zeros() as usize;
    let (x, y) = (max(x, y), min(x, y));
    if k < x - y || x - 1 + y - 1 < k || (k - (x - y)) % 2 != 0 {
        println!("0");
        return;
    }
    let p = y - (k - (x - y)) / 2;
    assert!(x - p + y - p == k);
    let mut ans = ModInt::new((1 << (p - 1)) as u32);
    ans *= ModInt(2).pow((x - p) as u32);
    if p != y {
        ans *= ModInt(2).pow((y - p - 1) as u32);
    }
    for i in 1..=d {
        for j in 1..=(1 << (i - 1)) {
            ans *= ModInt(j as u32);
        }
    }
    ans *= ModInt((1 << (x - 1)) as u32).inv();
    if x == y {
        ans *= ModInt((1 << (y - 1)) as u32 - 1).inv();
    } else {
        ans *= ModInt((1 << (y - 1)) as u32).inv();
    }
    println!("{}", ans.0);
}

fn main() {
    run();
}
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