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LeetCode 743 · Solution & editorial
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.
Network Delay Time is a Graph Traversal Patterns (DFS & BFS) problem, in the Shortest Path (Dijkstra's Algorithm) subpattern. The pattern covers DFS/BFS traversal, topological sort, shortest paths, Union-Find, and MST
Master Dijkstra's algorithm for finding shortest paths in weighted graphs with non-negative edges.
The reference solution runs in O(E + N log N) time and O(E + N) space.
Network Delay Time has been reported in interviews at Amazon.
The full editorial is part of Pro
It explains the core insight, the complexity analysis and the common mistakes, with a worked solution.
Network Delay Time is a Graph Traversal Patterns (DFS & BFS) problem, in the Shortest Path (Dijkstra's Algorithm) subpattern. Once the approach above makes sense, write it yourself and then work through the neighbouring problems that reuse it.