結果

問題 No.1044 正直者大学
ユーザー akakimidori
提出日時 2020-05-01 21:59:47
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 10 ms / 2,000 ms
コード長 5,115 bytes
コンパイル時間 14,145 ms
コンパイル使用メモリ 378,688 KB
実行使用メモリ 6,656 KB
最終ジャッジ日時 2024-12-25 06:30:26
合計ジャッジ時間 15,614 ms
ジャッジサーバーID
(参考情報)
judge4 / judge1
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
sample AC * 2
other AC * 28
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 #
プレゼンテーションモードにする

// ---------- 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<'a>(&self, f: &mut std::fmt::Formatter<'a>) -> std::fmt::Result {
write!(f, "{}", self.0)
}
}
impl std::str::FromStr for ModInt {
type Err = std::num::ParseIntError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let val = s.parse::<u32>()?;
Ok(ModInt::new(val))
}
}
impl From<usize> for ModInt {
fn from(val: usize) -> ModInt {
ModInt((val % MOD as usize) as u32)
}
}
#[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 {
assert!(self.0 > 0);
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 ----------
//https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
(source = $s:expr, $($r:tt)*) => {
let mut iter = $s.split_whitespace();
input_inner!{iter, $($r)*}
};
($($r:tt)*) => {
let s = {
use std::io::Read;
let mut s = String::new();
std::io::stdin().read_to_string(&mut s).unwrap();
s
};
let mut iter = s.split_whitespace();
input_inner!{iter, $($r)*}
};
}
macro_rules! input_inner {
($iter:expr) => {};
($iter:expr, ) => {};
($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
let $var = read_value!($iter, $t);
input_inner!{$iter $($r)*}
};
}
macro_rules! read_value {
($iter:expr, ( $($t:tt),* )) => {
( $(read_value!($iter, $t)),* )
};
($iter:expr, [ $t:tt ; $len:expr ]) => {
(0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
};
($iter:expr, chars) => {
read_value!($iter, String).chars().collect::<Vec<char>>()
};
($iter:expr, usize1) => {
read_value!($iter, usize) - 1
};
($iter:expr, $t:ty) => {
$iter.next().unwrap().parse::<$t>().expect("Parse error")
};
}
//
fn run() {
input! {
n: usize,
m: usize,
k: usize,
}
let pc = Precalc::new(2 * (m + n));
let mut ans = ModInt::zero();
for i in 1.. {
if n < i || m - 1 < i - 1 || n - i + m - i < k {
break;
}
ans += pc.fact(n - 1) * pc.fact(m) * pc.comb(n - i + i, i) * pc.comb(m - 1, i - 1);
}
println!("{}", ans);
}
fn main() {
run();
}
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