struct Solution;
use std::collections::VecDeque;
impl Solution {
fn network_delay_time(times: Vec<Vec<i32>>, n: i32, k: i32) -> i32 {
let n = n as usize;
let k = k as usize - 1;
let mut graph: Vec<Vec<(usize, i32)>> = vec![vec![]; n];
for time in times {
let u = time[0] as usize - 1;
let v = time[1] as usize - 1;
let t = time[2];
graph[u].push((v, t));
}
let mut visited = vec![std::i32::MAX; n];
let mut queue = VecDeque::new();
visited[k] = 0;
queue.push_back(k);
while let Some(u) = queue.pop_front() {
for &(v, t) in &graph[u] {
if t + visited[u] < visited[v] {
visited[v] = t + visited[u];
queue.push_back(v);
}
}
}
let max = visited.into_iter().max().unwrap();
if max == std::i32::MAX {
-1
} else {
max
}
}
}
#[test]
fn test() {
let times = vec_vec_i32![[2, 1, 1], [2, 3, 1], [3, 4, 1]];
let n = 4;
let k = 2;
let res = 2;
assert_eq!(Solution::network_delay_time(times, n, k), res);
}