//---------- begin union_find ---------- #[allow(dead_code)] mod union_find { pub struct UF { p: Vec, } impl UF { pub fn new(n: usize) -> UF { UF {p: vec![-1; n] } } pub fn init(&mut self) { for p in self.p.iter_mut() { *p = -1; } } pub fn root(&self, mut x: usize) -> usize { while self.p[x] >= 0 { x = self.p[x] as usize; } x } pub fn same(&self, x: usize, y: usize) -> bool { self.root(x) == self.root(y) } pub fn unite(&mut self, mut x: usize, mut y: usize) -> Option<(usize, usize)> { x = self.root(x); y = self.root(y); if x == y { return None; } if self.p[x] > self.p[y] { let s = x; x = y; y = s; } self.p[x] += self.p[y]; self.p[y] = x as i32; Some((x, y)) } pub fn get_size(&self, x: usize) -> usize { let r = self.root(x); (-self.p[r]) as usize } } } //---------- end union_find ---------- //https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 より 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, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } // fn calc(g: &[Vec], src: usize) -> bool { let mut elem = vec![false; g.len()]; let mut q = std::collections::VecDeque::new(); elem[src] = true; q.push_back(src); while let Some(v) = q.pop_front() { for &u in g[v].iter() { if u == src { return true; } if !elem[u] { elem[u] = true; q.push_back(u); } } } false } fn run() { input! { n: usize, m: usize, e: [(usize1, usize1, usize); m], } let mut u = union_find::UF::new(n); for &(a, b, c) in e.iter() { if c == 1 { u.unite(a, b); } } let mut id = vec![n; n]; let mut k = 0; for i in 0..n { let r = u.root(i); if id[r] == n { id[r] = k; k += 1; } } let mut graph = vec![vec![]; k]; for &(a, b, c) in e.iter() { if c == 2 { let a = u.root(a); let b = u.root(b); graph[id[a]].push(id[b]); } } if calc(&graph, id[u.root(0)]) { println!("Yes"); return; } let mut graph = vec![vec![]; n]; let mut k = 0; for &(a, b, c) in e.iter() { if c == 1 { graph[a].push((b, k)); graph[b].push((a, k)); k += 1; } } let g = graph; let mut elem = vec![false; g.len()]; let mut q = std::collections::VecDeque::new(); elem[0] = true; q.push_back((0, k)); while let Some((v, p)) = q.pop_front() { for &(u, k) in g[v].iter() { if k != p && u == 0 { println!("Yes"); return; } if !elem[u] { elem[u] = true; q.push_back((u, k)); } } } println!("No"); } fn main() { run(); }