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LeetCode 2045 · Solution & editorial
A city is represented as a bi-directional connected graph with n vertices where each vertex is labeled from 1 to n (inclusive). The edges in the graph are represented as a 2D integer array edges, where each edges[i] = [ui, vi] denotes a bi-directional edge between vertex ui and vertex vi. Every vertex pair is connected by at most one edge, and no vertex has an edge to itself. The time taken to traverse any edge is time minutes.
Second Minimum Time to Reach Destination 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(|V| + |E|) time and O(|V| + |E|) space.
The full editorial is part of Pro
It explains the core insight, the complexity analysis and the common mistakes, with a worked solution.
Second Minimum Time to Reach Destination 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.