LeetCode 743 Network Delay Time - Problem Statement

Problem: Network Delay Time Task: You have a network of $n$ nodes with weighted directed edges. Signal starts from node $k$. Find the minimum time for all nodes to receive the signal.

If impossible, return $-1$. Run Dijkstra from node $k$. The answer is the maximum distance among all reachable nodes. If any node is unreachable, return $-1$. This is a direct application of single-source shortest paths. The "delay time" is the longest shortest path from the source.