結果
問題 | No.827 総神童数 |
ユーザー |
|
提出日時 | 2024-09-08 21:46:32 |
言語 | Rust (1.83.0 + proconio) |
結果 |
AC
|
実行時間 | 120 ms / 2,000 ms |
コード長 | 4,045 bytes |
コンパイル時間 | 14,814 ms |
コンパイル使用メモリ | 388,268 KB |
実行使用メモリ | 40,096 KB |
最終ジャッジ日時 | 2024-09-08 21:46:52 |
合計ジャッジ時間 | 18,989 ms |
ジャッジサーバーID (参考情報) |
judge3 / judge5 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 36 |
ソースコード
use proconio::{input, marker::Usize1};fn main() {input! {n:usize,uv:[(Usize1,Usize1);n-1],}let mut g = vec![vec![]; n];for &(u, v) in uv.iter() {g[u].push(v);g[v].push(u);}let mut cnts = vec![0; n];dfs(0, n, &g, &mut cnts, 0);let mut facs = vec![ModInt::<MOD>::new(1); n + 1];for i in 0..n {facs[i + 1] = facs[i] * ModInt::new(i + 1);}let mut f = vec![ModInt::new(0); n];for i in 0..n {f[i] = facs[n - i - 1] * ModInt::new(n - i) * facs[n] / (ModInt::new(i + 1) * facs[n - i]);}let mut ans = ModInt::new(0);for i in 0..n {ans += f[cnts[i]];}println!("{}", ans);}fn dfs(crr: usize, prv: usize, g: &Vec<Vec<usize>>, cnts: &mut Vec<usize>, cnt: usize) {cnts[crr] = cnt;for &nxt in g[crr].iter() {if nxt == prv {continue;}dfs(nxt, crr, g, cnts, cnt + 1);}}const MOD: usize = 1000000007;use modint::*;mod modint {use std::fmt;use std::ops;#[derive(Copy, Clone, PartialEq, Eq)]pub struct ModInt<const MOD: usize> {pub val: usize,}impl<const MOD: usize> ModInt<MOD> {pub fn new(val: usize) -> Self {Self { val: val % MOD }}pub fn pow(mut self, mut e: usize) -> Self {let mut res = Self::new(1);while 0 < e {if e & 1 != 0 {res *= self;}self *= self;e >>= 1;}res}}impl<const MOD: usize> From<usize> for ModInt<MOD> {fn from(value: usize) -> Self {Self { val: value % MOD }}}impl<const MOD: usize> fmt::Display for ModInt<MOD> {fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {write!(f, "{}", self.val)}}impl<const MOD: usize> fmt::Debug for ModInt<MOD> {fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {write!(f, "{}", self.val)}}impl<const MOD: usize> ops::Neg for ModInt<MOD> {type Output = Self;fn neg(self) -> Self::Output {Self {val: (MOD - self.val) % MOD,}}}impl<const MOD: usize> ops::Add for ModInt<MOD> {type Output = Self;fn add(self, rhs: Self) -> Self::Output {Self {val: (self.val + rhs.val) % MOD,}}}impl<const MOD: usize> ops::AddAssign for ModInt<MOD> {fn add_assign(&mut self, rhs: Self) {*self = *self + rhs;}}impl<const MOD: usize> ops::Mul for ModInt<MOD> {type Output = Self;fn mul(self, rhs: Self) -> Self::Output {Self {val: self.val * rhs.val % MOD,}}}impl<const MOD: usize> ops::MulAssign for ModInt<MOD> {fn mul_assign(&mut self, rhs: Self) {*self = *self * rhs;}}impl<const MOD: usize> ops::Sub for ModInt<MOD> {type Output = Self;fn sub(mut self, rhs: Self) -> Self::Output {if self.val < rhs.val {self.val += MOD;}Self {val: (self.val - rhs.val) % MOD,}}}impl<const MOD: usize> ops::SubAssign for ModInt<MOD> {fn sub_assign(&mut self, rhs: Self) {if self.val < rhs.val {self.val += MOD;}*self = *self - rhs;}}impl<const MOD: usize> ops::Div for ModInt<MOD> {type Output = Self;fn div(self, rhs: Self) -> Self {assert!(rhs.val != 0);self * rhs.pow(MOD - 2)}}impl<const MOD: usize> ops::DivAssign for ModInt<MOD> {fn div_assign(&mut self, rhs: Self) {*self = *self / rhs}}}