結果

問題 No.2418 情報通だよ!Nafmoくん
ユーザー haihamabossu
提出日時 2023-08-12 13:48:26
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 42 ms / 2,000 ms
コード長 7,624 bytes
コンパイル時間 13,192 ms
コンパイル使用メモリ 391,336 KB
実行使用メモリ 17,396 KB
最終ジャッジ日時 2024-11-14 12:21:56
合計ジャッジ時間 14,121 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 * 21
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ソースコード

diff #
プレゼンテーションモードにする

//https://github.com/rust-lang-ja/ac-library-rs
pub mod dsu {
//! A Disjoint set union (DSU) with union by size and path compression.
/// A Disjoint set union (DSU) with union by size and path compression.
///
/// See: [Zvi Galil and Giuseppe F. Italiano, Data structures and algorithms for disjoint set union problems](https://core.ac.uk/download/pdf
        /161439519.pdf)
///
/// In the following documentation, let $n$ be the size of the DSU.
///
/// # Example
///
/// ```
/// use ac_library::Dsu;
/// use proconio::{input, source::once::OnceSource};
///
/// input! {
/// from OnceSource::from(
/// "5\n\
/// 3\n\
/// 0 1\n\
/// 2 3\n\
/// 3 4\n",
/// ),
/// n: usize,
/// abs: [(usize, usize)],
/// }
///
/// let mut dsu = Dsu::new(n);
/// for (a, b) in abs {
/// dsu.merge(a, b);
/// }
///
/// assert!(dsu.same(0, 1));
/// assert!(!dsu.same(1, 2));
/// assert!(dsu.same(2, 4));
///
/// assert_eq!(
/// dsu.groups()
/// .into_iter()
/// .map(|mut group| {
/// group.sort_unstable();
/// group
/// })
/// .collect::<Vec<_>>(),
/// [&[0, 1][..], &[2, 3, 4][..]],
/// );
/// ```
pub struct Dsu {
n: usize,
// root node: -1 * component size
// otherwise: parent
parent_or_size: Vec<i32>,
}
impl Dsu {
/// Creates a new `Dsu`.
///
/// # Constraints
///
/// - $0 \leq n \leq 10^8$
///
/// # Complexity
///
/// - $O(n)$
pub fn new(size: usize) -> Self {
Self {
n: size,
parent_or_size: vec![-1; size],
}
}
// `\textsc` does not work in KaTeX
/// Performs the Uɴɪᴏɴ operation.
///
/// # Constraints
///
/// - $0 \leq a < n$
/// - $0 \leq b < n$
///
/// # Panics
///
/// Panics if the above constraints are not satisfied.
///
/// # Complexity
///
/// - $O(\alpha(n))$ amortized
pub fn merge(&mut self, a: usize, b: usize) -> usize {
assert!(a < self.n);
assert!(b < self.n);
let (mut x, mut y) = (self.leader(a), self.leader(b));
if x == y {
return x;
}
if -self.parent_or_size[x] < -self.parent_or_size[y] {
std::mem::swap(&mut x, &mut y);
}
self.parent_or_size[x] += self.parent_or_size[y];
self.parent_or_size[y] = x as i32;
x
}
/// Returns whether the vertices $a$ and $b$ are in the same connected component.
///
/// # Constraints
///
/// - $0 \leq a < n$
/// - $0 \leq b < n$
///
/// # Panics
///
/// Panics if the above constraint is not satisfied.
///
/// # Complexity
///
/// - $O(\alpha(n))$ amortized
pub fn same(&mut self, a: usize, b: usize) -> bool {
assert!(a < self.n);
assert!(b < self.n);
self.leader(a) == self.leader(b)
}
/// Performs the Fɪɴᴅ operation.
///
/// # Constraints
///
/// - $0 \leq a < n$
///
/// # Panics
///
/// Panics if the above constraint is not satisfied.
///
/// # Complexity
///
/// - $O(\alpha(n))$ amortized
pub fn leader(&mut self, a: usize) -> usize {
assert!(a < self.n);
if self.parent_or_size[a] < 0 {
return a;
}
self.parent_or_size[a] = self.leader(self.parent_or_size[a] as usize) as i32;
self.parent_or_size[a] as usize
}
/// Returns the size of the connected component that contains the vertex $a$.
///
/// # Constraints
///
/// - $0 \leq a < n$
///
/// # Panics
///
/// Panics if the above constraint is not satisfied.
///
/// # Complexity
///
/// - $O(\alpha(n))$ amortized
pub fn size(&mut self, a: usize) -> usize {
assert!(a < self.n);
let x = self.leader(a);
-self.parent_or_size[x] as usize
}
/// Divides the graph into connected components.
///
/// The result may not be ordered.
///
/// # Complexity
///
/// - $O(n)$
pub fn groups(&mut self) -> Vec<Vec<usize>> {
let mut leader_buf = vec![0; self.n];
let mut group_size = vec![0; self.n];
for i in 0..self.n {
leader_buf[i] = self.leader(i);
group_size[leader_buf[i]] += 1;
}
let mut result = vec![Vec::new(); self.n];
for i in 0..self.n {
result[i].reserve(group_size[i]);
}
for i in 0..self.n {
result[leader_buf[i]].push(i);
}
result
.into_iter()
.filter(|x| !x.is_empty())
.collect::<Vec<Vec<usize>>>()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn dsu_works() {
let mut d = Dsu::new(4);
d.merge(0, 1);
assert!(d.same(0, 1));
d.merge(1, 2);
assert!(d.same(0, 2));
assert_eq!(d.size(0), 3);
assert!(!d.same(0, 3));
assert_eq!(d.groups(), vec![vec![0, 1, 2], vec![3]]);
}
}
}
use dsu::*;
pub mod scanner {
pub struct Scanner {
buf: Vec<String>,
}
impl Scanner {
pub fn new() -> Self {
Self { buf: vec![] }
}
pub fn new_from(source: &str) -> Self {
let source = String::from(source);
let buf = Self::split(source);
Self { buf }
}
pub fn next<T: std::str::FromStr>(&mut self) -> T {
loop {
if let Some(x) = self.buf.pop() {
return x.parse().ok().expect("");
}
let mut source = String::new();
std::io::stdin().read_line(&mut source).expect("");
self.buf = Self::split(source);
}
}
fn split(source: String) -> Vec<String> {
source
.split_whitespace()
.rev()
.map(String::from)
.collect::<Vec<_>>()
}
}
}
use crate::scanner::Scanner;
use crate::Dsu;
use std::io::Write;
fn main() {
let mut scanner = Scanner::new();
let out = std::io::stdout();
let mut out = std::io::BufWriter::new(out.lock());
let t: usize = 1;
for _ in 0..t {
solve(&mut scanner, &mut out);
}
}
fn solve(scanner: &mut Scanner, out: &mut std::io::BufWriter<std::io::StdoutLock>) {
let n: usize = scanner.next();
let m: usize = scanner.next();
let mut dsu = Dsu::new(n * 2);
for _ in 0..m {
let a: usize = scanner.next();
let b: usize = scanner.next();
dsu.merge(a - 1, b - 1);
}
let mut ans = 0usize;
for g in dsu.groups().iter() {
if g.len() % 2 == 1 {
ans += 1;
}
}
ans /= 2;
writeln!(out, "{}", ans).unwrap();
}
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