結果
| 問題 | No.196 典型DP (1) |
| ユーザー |
 togatoga
|
| 提出日時 | 2021-11-25 13:49:34 |
| 言語 | Rust (1.83.0 + proconio) |
| 結果 |
AC
|
| 実行時間 | 54 ms / 2,000 ms |
| コード長 | 11,920 bytes |
| コンパイル時間 | 23,954 ms |
| コンパイル使用メモリ | 402,320 KB |
| 実行使用メモリ | 33,920 KB |
| 最終ジャッジ日時 | 2024-06-28 05:03:53 |
| 合計ジャッジ時間 | 18,203 ms |
|
ジャッジサーバーID （参考情報） |
judge3 / judge4 |
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| ファイルパターン | 結果 |
|---|---|
| sample | AC * 3 |
| other | AC * 41 |
ソースコード
use mod_int::ModInt1000000007;
pub mod utils {
const DYX: [(isize, isize); 8] = [
(0, 1),
(1, 0),
(0, -1),
(-1, 0),
(1, 1),
(-1, 1),
(1, -1),
(-1, -1),
];
pub fn try_adj(y: usize, x: usize, dir: usize, h: usize, w: usize) -> Option<(usize, usize)> {
let ny = y as isize + DYX[dir].0;
let nx = x as isize + DYX[dir].1;
if ny >= 0 && nx >= 0 && ny < h as isize && nx < w as isize {
Some((ny as usize, nx as usize))
} else {
None
}
}
}
/// Modular Integer
/// NOTE
/// If a modular isn't prime, you can't div.
/// If you want to calculate a combination and permutation, you have to use `mod_comb`.
pub mod mod_int {
use std::marker::PhantomData;
use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
pub struct Mod1000000007;
#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
pub struct Mod998244353;
pub trait Modulus: Copy + Eq + Copy {
const VALUE: u32;
}
impl Modulus for Mod1000000007 {
const VALUE: u32 = 1000000007;
}
impl Modulus for Mod998244353 {
const VALUE: u32 = 998244353;
}
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct ModInt<
T: Copy + Clone + Add + AddAssign + Mul + MulAssign + Sub + SubAssign,
M: Modulus,
> {
pub val: T,
phantom: std::marker::PhantomData<fn() -> M>,
}
/// Implementation macros
#[warn(unused_macros)]
macro_rules ! mod_int_impl {($ ($ t : ty ) * ) => ($ (impl < M : Modulus > ModInt <$ t , M > {pub fn new (x : $ t ) -> Self {ModInt {val : x % M :: VALUE as $ t , phantom : PhantomData } } pub fn pow (self , e : usize ) -> ModInt <$ t , M > {let mut result = ModInt ::<$ t , M >:: new (1 ) ; let mut cur = self ; let mut e = e ; while e > 0 {if e & 1 == 1 {result *= cur ; } cur *= cur ; e >>= 1 ; } result } } impl < M : Modulus > Add < ModInt <$ t , M >> for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn add (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {self + rhs . val } } impl < M : Modulus > Add < ModInt <$ t , M >> for $ t {type Output = ModInt <$ t , M >; fn add (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {let x = self % M :: VALUE as $ t ; let val = (x + rhs . val ) % M :: VALUE as $ t ; ModInt {val , phantom : PhantomData } } } impl < M : Modulus > Add <$ t > for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn add (self , rhs : $ t ) -> ModInt <$ t , M > {let x = rhs % M :: VALUE as $ t ; let val = (self . val + x ) % M :: VALUE as $ t ; ModInt {val , phantom : PhantomData } } } impl < M : Modulus > Sub < ModInt <$ t , M >> for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn sub (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {self - rhs . val } } impl < M : Modulus > Sub < ModInt <$ t , M >> for $ t {type Output = ModInt <$ t , M >; fn sub (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {let val = self % M :: VALUE as $ t ; ModInt {val , phantom : PhantomData } - rhs } } impl < M : Modulus > Sub <$ t > for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn sub (self , rhs : $ t ) -> ModInt <$ t , M > {let rhs = if rhs >= M :: VALUE as $ t {rhs % M :: VALUE as $ t } else {rhs } ; let val = if self . val < rhs {self . val + M :: VALUE as $ t - rhs } else {self . val - rhs } ; ModInt {val , phantom : PhantomData } } } impl < M : Modulus > AddAssign < ModInt <$ t , M >> for ModInt <$ t , M > {fn add_assign (& mut self , rhs : ModInt <$ t , M > ) {* self = * self + rhs ; } } impl < M : Modulus > AddAssign <$ t > for ModInt <$ t , M > {fn add_assign (& mut self , rhs : $ t ) {* self = * self + rhs ; } } impl < M : Modulus > SubAssign < ModInt <$ t , M >> for ModInt <$ t , M > {fn sub_assign (& mut self , rhs : ModInt <$ t , M > ) {* self = * self - rhs ; } } impl < M : Modulus > SubAssign <$ t > for ModInt <$ t , M > {fn sub_assign (& mut self , rhs : $ t ) {* self = * self - rhs ; } } impl < M : Modulus > Div <$ t > for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn div (self , mut rhs : $ t ) -> ModInt <$ t , M > {if rhs >= M :: VALUE as $ t {rhs %= M :: VALUE as $ t ; } self * ModInt {val : rhs , phantom : PhantomData } . pow ((M :: VALUE - 2 ) as usize ) } } impl < M : Modulus > Div < ModInt <$ t , M >> for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn div (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {self / rhs . val } } impl < M : Modulus > DivAssign <$ t > for ModInt <$ t , M > {fn div_assign (& mut self , rhs : $ t ) {* self = * self / rhs } } impl < M : Modulus > DivAssign < ModInt <$ t , M >> for ModInt <$ t , M > {fn div_assign (& mut self , rhs : ModInt <$ t , M > ) {* self = * self / rhs } } impl < M : Modulus > Mul < ModInt <$ t , M >> for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn mul (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {self * rhs . val } } impl < M : Modulus > Mul < ModInt <$ t , M >> for $ t {type Output = ModInt <$ t , M >; fn mul (self , rhs : ModInt <$ t , M > ) -> ModInt <$ t , M > {rhs * self } } impl < M : Modulus > Mul <$ t > for ModInt <$ t , M > {type Output = ModInt <$ t , M >; fn mul (self , rhs : $ t ) -> ModInt <$ t , M > {ModInt {val : self . val * (rhs % M :: VALUE as $ t ) % M :: VALUE as $ t , phantom : PhantomData } } } impl < M : Modulus > MulAssign < ModInt <$ t , M >> for ModInt <$ t , M > {fn mul_assign (& mut self , rhs : ModInt <$ t , M > ) {* self = * self * rhs ; } } impl < M : Modulus > MulAssign <$ t > for ModInt <$ t , M > {fn mul_assign (& mut self , rhs : $ t ) {* self = * self * rhs ; } } impl < M : Modulus > Default for ModInt <$ t , M > {fn default () -> ModInt <$ t , M > {ModInt {val : 0 , phantom : PhantomData } } } ) * ) }
mod_int_impl ! (usize i64 u64 i128 );
#[allow(dead_code)]
pub type ModInt1000000007 = ModInt<i64, Mod1000000007>;
pub type ModInt998244353 = ModInt<i64, Mod998244353>;
}
#[derive(Default)]
/// NOTE
/// declare variables to reduce the number of parameters for dp and dfs etc.
pub struct Solver {
edges: Vec<Vec<usize>>,
dp: Vec<Vec<ModInt1000000007>>,
sum: Vec<usize>,
}
impl Solver {
pub fn dfs(&mut self, pos: usize, pre: Option<usize>) {
let m = self.edges[pos].len();
let n = self.sum.len();
self.dp[pos][0] += 1;
//cecho!(pos, pre, &self.dp[pos]);
for i in 0..m {
let nxt = self.edges[pos][i];
if Some(nxt) == pre {
continue;
}
self.dfs(nxt, Some(pos));
let mut tmps = vec![ModInt1000000007::new(0); n + 1];
for x in 0..=self.sum[pos] {
for y in 0..=self.sum[nxt] {
tmps[x + y] += self.dp[pos][x] * self.dp[nxt][y];
}
}
self.dp[pos] = tmps;
self.sum[pos] += self.sum[nxt];
}
self.sum[pos] += 1;
self.dp[pos][self.sum[pos]] += 1;
}
pub fn solve(&mut self) {
let stdin = std::io::stdin();
#[allow(unused_mut, unused_variables)]
let mut scn = fastio::Scanner::new(stdin.lock());
let n: usize = scn.read();
let k: usize = scn.read();
let mut edges = vec![vec![]; n];
for _ in 0..n-1 {
let x: usize = scn.read();
let y: usize = scn.read();
edges[x].push(y);
edges[y].push(x);
}
self.sum = vec![0; n];
self.dp = vec![vec![ModInt1000000007::new(0); n + 1]; n + 1];
self.edges = edges;
self.dfs(0, None);
let result = self.dp[0][k];
println!("{}", result.val);
}
}
pub mod fastio {
use std::collections::VecDeque;
use std::io::BufWriter;
use std::io::Write;
pub struct Writer<W: std::io::Write> {
writer: std::io::BufWriter<W>,
}
impl<W: std::io::Write> Writer<W> {
pub fn new(write: W) -> Writer<W> {
Writer {
writer: BufWriter::new(write),
}
}
pub fn flush(&mut self) {
self.writer.flush().unwrap();
}
pub fn write<S: std::string::ToString>(&mut self, s: S) {
self.writer.write(s.to_string().as_bytes()).unwrap();
}
pub fn writeln<S: std::string::ToString>(&mut self, s: S) {
self.write(s);
self.write('\n');
}
}
pub struct Scanner<R> {
stdin: R,
buffer: VecDeque<String>,
}
impl<R: std::io::BufRead> Scanner<R> {
pub fn new(s: R) -> Scanner<R> {
Scanner {
stdin: s,
buffer: VecDeque::new(),
}
}
pub fn read<T: std::str::FromStr>(&mut self) -> T {
while self.buffer.is_empty() {
let line = self.read_line();
for w in line.split_whitespace() {
self.buffer.push_back(String::from(w));
}
}
self.buffer.pop_front().unwrap().parse::<T>().ok().unwrap()
}
pub fn read_line(&mut self) -> String {
let mut line = String::new();
let _ = self.stdin.read_line(&mut line);
line.trim_end().to_string()
}
pub fn vec<T: std::str::FromStr>(&mut self, n: usize) -> Vec<T> {
(0..n).map(|_| self.read()).collect()
}
pub fn chars(&mut self) -> Vec<char> {
self.read::<String>().chars().collect()
}
}
}
pub mod macros {
#[macro_export]
#[allow(unused_macros)]
macro_rules ! max {($ x : expr ) => ($ x ) ; ($ x : expr , $ ($ y : expr ) ,+ ) => {std :: cmp :: max ($ x , max ! ($ ($ y ) ,+ ) ) } }
#[macro_export]
#[allow(unused_macros)]
macro_rules ! min {($ x : expr ) => ($ x ) ; ($ x : expr , $ ($ y : expr ) ,+ ) => {std :: cmp :: min ($ x , min ! ($ ($ y ) ,+ ) ) } }
#[macro_export]
#[allow(unused_macros)]
/// Display a line of variables
macro_rules ! echo {() => {{use std :: io :: {self , Write } ; writeln ! (io :: stderr () , "{}:" , line ! () ) . unwrap () ; } } ; ($ e : expr , $ ($ es : expr ) ,+ $ (, ) ? ) => {{use std :: io :: {self , Write } ; write ! (io :: stderr () , "{}:" , line ! () ) . unwrap () ; write ! (io :: stderr () , " {} = {:?}" , stringify ! ($ e ) , $ e ) . unwrap () ; $ (write ! (io :: stderr () , " {} = {:?}" , stringify ! ($ es ) , $ es ) . unwrap () ; ) + writeln ! (io :: stderr () ) . unwrap () ; } } ; ($ e : expr ) => {{use std :: io :: {self , Write } ; let result = $ e ; writeln ! (io :: stderr () , "{}: {} = {:?}" , line ! () , stringify ! ($ e ) , result ) . unwrap () ; result } } ; }
#[macro_export]
#[allow(unused_macros)]
/// Display a line of variables with colors
macro_rules ! cecho {() => {{use std :: io :: {self , Write } ; writeln ! (io :: stderr () , "\x1b[31;1m{}\x1b[m:" , line ! () ) . unwrap () ; } } ; ($ e : expr , $ ($ es : expr ) ,+ $ (, ) ? ) => {{use std :: io :: {self , Write } ; write ! (io :: stderr () , "\x1b[31;1m{}\x1b[m:" , line ! () ) . unwrap () ; write ! (io :: stderr () , " \x1b[92;1m{}\x1b[m = {:?}" , stringify ! ($ e ) , $ e ) . unwrap () ; $ (write ! (io :: stderr () , " \x1b[92;1m{}\x1b[m = {:?}" , stringify ! ($ es ) , $ es ) . unwrap () ; ) + writeln ! (io :: stderr () ) . unwrap () ; } } ; ($ e : expr ) => {{use std :: io :: {self , Write } ; let result = $ e ; writeln ! (io :: stderr () , "\x1b[31;1m{}\x1b[m: \x1b[92;1m{}\x1b[m = {:?}" , line ! () , stringify ! ($ e ) , result ) . unwrap () ; result } } ; }
}
fn main() {
std::thread::Builder::new()
.stack_size(64 * 1024 * 1024)
.spawn(|| Solver::default().solve())
.unwrap()
.join()
.unwrap();
}