Concrete implementation of Dijkstra's algorithm for finding the shortest path in a weighted directed graph

Dijkstra's algorithm is an algorithm for finding the shortest path in a weighted directed graph. It can start from a specific vertex and search for the shortest path to all reachable nodes. Its basic idea is to select a shortest path from unvisited nodes each time, and then start from this node to search for the shortest paths of other reachable nodes until the final goal is found.