#628 · #743 · Network Delay Time(网络延迟时间)

You are given times where times[i] = [u, v, w] is a directed edge taking w time, and n nodes labelled 1..n. Starting from node k, return the time for all nodes to receive the signal, or -1 if impossible. Constraints: 1 <= k <= n <= 100, 1 <= times.length <= 6000, 0 <= w <= 100.