20240105 Finished

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jackfiled 2024-01-05 19:41:11 +08:00
parent 6b6228f712
commit d4132e91d4
2 changed files with 130 additions and 0 deletions

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@ -12,3 +12,4 @@ mod s1276_number_of_burgers_with_no_waste_of_ingredients;
mod s0006_zigzag_conversion;
mod s0007_reverse_integer;
mod s0004_median_of_two_sorted_arrays;
mod s0743_network_delay_time;

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/**
* [743] Network Delay Time
*
* You are given a network of n nodes, labeled from 1 to n. You are also given times, a list of travel times as directed edges times[i] = (ui, vi, wi), where ui is the source node, vi is the target node, and wi is the time it takes for a signal to travel from source to target.
* We will send a signal from a given node k. Return the minimum time it takes for all the n nodes to receive the signal. If it is impossible for all the n nodes to receive the signal, return -1.
*
* <strong class="example">Example 1:
* <img alt="" src="https://assets.leetcode.com/uploads/2019/05/23/931_example_1.png" style="width: 217px; height: 239px;" />
* Input: times = [[2,1,1],[2,3,1],[3,4,1]], n = 4, k = 2
* Output: 2
*
* <strong class="example">Example 2:
*
* Input: times = [[1,2,1]], n = 2, k = 1
* Output: 1
*
* <strong class="example">Example 3:
*
* Input: times = [[1,2,1]], n = 2, k = 2
* Output: -1
*
*
* Constraints:
*
* 1 <= k <= n <= 100
* 1 <= times.length <= 6000
* times[i].length == 3
* 1 <= ui, vi <= n
* ui != vi
* 0 <= wi <= 100
* All the pairs (ui, vi) are unique. (i.e., no multiple edges.)
*
*/
pub struct Solution {}
// problem: https://leetcode.cn/problems/network-delay-time/
// discuss: https://leetcode.cn/problems/network-delay-time/discuss/?currentPage=1&orderBy=most_votes&query=
// submission codes start here
use std::cmp::{max, min};
use std::collections::HashSet;
impl Solution {
pub fn network_delay_time(times: Vec<Vec<i32>>, n: i32, k: i32) -> i32 {
let n = n as usize;
let k = k as usize;
let mut matrix = Vec::with_capacity(n + 1);
for _i in 0..=n {
let mut line = Vec::with_capacity(n + 1);
line.resize(n + 1, i32::MAX);
matrix.push(line);
}
for line in &times {
matrix[line[0] as usize][line[1] as usize] = line[2];
}
let mut path = HashSet::with_capacity(n + 1);
path.insert(k);
let mut distances = matrix[k].clone();
for _ in 2..=n {
let (mut index, mut value) = (0usize, i32::MAX);
for (i, d) in distances.iter().enumerate() {
if path.contains(&i) {
continue;
}
if value > *d {
value = *d;
index = i;
}
}
if value == i32::MAX {
break;
}
path.insert(index);
for i in 1..=n {
if path.contains(&i) {
continue;
}
if matrix[index][i] == i32::MAX {
continue;
}
distances[i] = min(distances[i], value + matrix[index][i]);
}
}
let mut result = i32::MIN;
for i in 1..distances.len() {
if i == k {
continue
}
result = max(result, distances[i]);
}
return if result == i32::MAX {
-1
} else {
result
}
}
}
// submission codes end
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_743() {
assert_eq!(Solution::network_delay_time(
vec![vec![2,1,1], vec![2,3,1], vec![3,4,1]], 4, 2), 2);
assert_eq!(Solution::network_delay_time(vec![vec![1,2,1]], 2, 1), 1);
assert_eq!(Solution::network_delay_time(vec![vec![1,2,1]], 2, 2), -1);
}
}