use std::collections::*; // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 macro_rules! input { ($($r:tt)*) => { let stdin = std::io::stdin(); let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock())); let mut next = move || -> String{ bytes.by_ref().map(|r|r.unwrap() as char) .skip_while(|c|c.is_whitespace()) .take_while(|c|!c.is_whitespace()) .collect() }; input_inner!{next, $($r)*} }; } macro_rules! input_inner { ($next:expr) => {}; ($next:expr,) => {}; ($next:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($next, $t); input_inner!{$next $($r)*} }; } macro_rules! read_value { ($next:expr, ( $($t:tt),* )) => { ($(read_value!($next, $t)),*) }; ($next:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($next, $t)).collect::>() }; ($next:expr, usize1) => (read_value!($next, usize) - 1); ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error")); } fn main() { input! { n: usize, m: usize, k: usize, uvc: [(usize1, usize1, i64); m], } let mut g = vec![vec![]; n]; for &(u, v, c) in &uvc { g[u].push((v, c)); g[v].push((u, c)); } let mut fail = 200_100; let mut pass = 0; while fail - pass > 1 { let mid = (fail + pass) / 2; let mut que = VecDeque::new(); const INF: usize = 1 << 20; let mut dist = vec![INF; n]; que.push_back((0, 0)); while let Some((d, v)) = que.pop_front() { if dist[v] <= d { continue; } dist[v] = d; for &(w, c) in &g[v] { if c >= mid { que.push_back((d + 1, w)); } else { que.push_front((d, w)); } } } if dist[n - 1] >= k { pass = mid; } else { fail = mid; } } println!("{}", pass); }