# 0743. Network Delay Time

https://leetcode.com/problems/network-delay-time

## Description

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 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`.

**Example 1:**

![](https://assets.leetcode.com/uploads/2019/05/23/931_example_1.png)

```
**Input:** times = [[2,1,1],[2,3,1],[3,4,1]], n = 4, k = 2
**Output:** 2
```

**Example 2:**

```
**Input:** times = [[1,2,1]], n = 2, k = 1
**Output:** 1
```

**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.)

## ac

```java
```
