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:

**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.)

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