#![allow(unused)] use kyoproio::*; use std::{ collections::*, io::{self, prelude::*}, iter, mem::{replace, swap}, }; fn main() -> io::Result<()> { std::thread::Builder::new() .stack_size(10 * 1024 * 1024) .spawn(solve)? .join() .unwrap(); Ok(()) } fn solve() { let stdin = io::stdin(); let mut kin = KInput::new(stdin.lock()); let stdout = io::stdout(); let mut out = io::BufWriter::new(stdout.lock()); macro_rules! output { ($($args:expr),+) => { write!(&mut out, $($args),+) }; } macro_rules! outputln { ($($args:expr),+) => { output!($($args),+); outputln!(); }; () => { output!("\n"); if cfg!(debug_assertions) { out.flush(); } } } let (n, m): (usize, usize) = kin.input(); let mut uf = UnionFind::new(n + 1); let mut g = vec![vec![]; n + 1]; let mut cy = false; for (a, b, c) in kin.iter::<(usize, usize, char)>().take(m) { match c { '1' => if !uf.unite(a, b) { cy = true; } '2' => g[a].push(b), _ => {} } } if cy { outputln!("Yes"); return; } let mut h = vec![vec![]; n + 1]; for u in 1..=n { for &v in &g[u] { let ru = uf.root(u); let rv = uf.root(v); if ru == rv { outputln!("Yes"); return; } h[ru].push(rv); } } let scc = strongly_connected_components(&h); for c in scc { if c.len() >= 2 { outputln!("Yes"); return; } } outputln!("No"); } pub struct UnionFind { p: Vec, } impl UnionFind { pub fn new(n: usize) -> Self { Self { p: vec![-1; n] } } pub fn root(&self, mut u: usize) -> usize { while self.p[u] >= 0 { u = self.p[u] as usize; } u } pub fn size(&self, u: usize) -> usize { (-self.p[self.root(u)]) as usize } pub fn unite(&mut self, u: usize, v: usize) -> bool { let mut u = self.root(u); let mut v = self.root(v); if u == v { return false; } if self.p[u] > self.p[v] { swap(&mut u, &mut v); } self.p[u] += self.p[v]; self.p[v] = u as isize; true } pub fn is_same(&self, u: usize, v: usize) -> bool { self.root(u) == self.root(v) } } fn strongly_connected_components(g: &[Vec]) -> Vec> { let mut ord = Vec::with_capacity(g.len()); let mut vis = vec![false; g.len()]; for u in 0..g.len() { if !vis[u] { dfs_f(g, u, &mut ord, &mut vis); } } let mut comps = Vec::new(); let mut h = vec![Vec::new(); g.len()]; for u in 0..g.len() { for &v in &g[u] { h[v].push(u); } } vis.iter_mut().for_each(|v| *v = false); for u in ord.into_iter().rev() { if !vis[u] { let mut comp = Vec::new(); dfs_c(&h, u, &mut comp, &mut vis); comps.push(comp); } } comps } fn dfs_f(g: &[Vec], u: usize, ord: &mut Vec, vis: &mut [bool]) { vis[u] = true; for &v in &g[u] { if !vis[v] { dfs_f(g, v, ord, vis); } } ord.push(u); } fn dfs_c(h: &[Vec], u: usize, comp: &mut Vec, vis: &mut [bool]) { vis[u] = true; comp.push(u); for &v in &h[u] { if !vis[v] { dfs_c(h, v, comp, vis); } } } // ----------------------------------------------------------------------------- pub mod kyoproio { #![warn(unused)] use std::io::prelude::*; pub trait Input { fn str(&mut self) -> &str; fn bytes(&mut self) -> &[u8] { self.str().as_ref() } fn input(&mut self) -> T { T::input(self).expect("input error") } fn iter(&mut self) -> Iter { Iter(self, std::marker::PhantomData) } fn seq>(&mut self, n: usize) -> B { self.iter().take(n).collect() } } pub struct KInput { src: R, buf: String, pos: usize, } impl KInput { pub fn new(src: R) -> Self { Self { src, buf: String::with_capacity(1024), pos: 0, } } } impl Input for KInput { fn str(&mut self) -> &str { loop { if self.pos >= self.buf.len() { self.pos = 0; self.buf.clear(); if self.src.read_line(&mut self.buf).expect("io error") == 0 { return &self.buf; } } let range = self.pos ..self.buf[self.pos..] .find(|c: char| c.is_ascii_whitespace()) .map(|i| i + self.pos) .unwrap_or_else(|| self.buf.len()); self.pos = range.end + 1; if range.end > range.start { return &self.buf[range]; } } } } pub struct Iter<'a, T, I: ?Sized>(&'a mut I, std::marker::PhantomData<*const T>); impl<'a, T: InputParse, I: Input + ?Sized> Iterator for Iter<'a, T, I> { type Item = T; fn next(&mut self) -> Option { Some(self.0.input()) } } pub trait InputParse: Sized { type Err: std::fmt::Debug; fn input(input: &mut I) -> Result; } macro_rules! from_str_impls { { $($T:ty)* } => { $(impl InputParse for $T { type Err = <$T as std::str::FromStr>::Err; fn input(input: &mut I) -> Result { input.str().parse::<$T>() } })* }; } from_str_impls! { String char bool f32 f64 isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 } macro_rules! tuple_impls { ($H:ident $($T:ident)*) => { impl<$H: InputParse, $($T: InputParse),*> InputParse for ($H, $($T),*) { type Err = std::convert::Infallible; fn input(input: &mut I) -> Result { // ? Ok(($H::input(input).unwrap(), $($T::input(input).unwrap()),*)) } } tuple_impls!($($T)*); }; () => {}; } tuple_impls!(A B C D E F G); }