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g0701_0800.s0743_network_delay_time.readme.md Maven / Gradle / Ivy

743\. Network Delay Time

Medium

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.)