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`.   **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.)