Calculate and return the network delay time if all “n” nodes in a network can be reached can be reached. If they cannot be reached return -1.

Input times -> [source, target, weight (time)]

n -> Number of nodes

k -> Source node

1<= k <= n <= 100

You can assume that there are no multi nodes.

The Bellman-Ford algorithm can be used to solve this.

Runtime: O(n^2)

```
const networkDelayTime = (times, n, k) => {
const distFromSource = new Array(n + 1); // Since, k >= 1.
distFromSource.fill(Number.MAX_VALUE, 1);
distFromSource[k] = 0;
// (n - 1) Edges.
for (let i = 0; i < n-1; i++) {
for (const time of times) {
if (distFromSource[time[0]] !== Number.MAX_VALUE && (distFromSource[time[0]] + time[2]) < distFromSource[time[1]]) {
distFromSource[time[1]] = distFromSource[time[0]] + time[2];
}
}
}
const max = Math.max(...distFromSource.slice(1));
return max === Number.MAX_VALUE ? -1 : max;
};
console.log(networkDelayTime([
[2, 1, 1],
[2, 3, 1],
[3, 4, 1]
], 4, 2));
// 2
```