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Aryan Kumar

Aryan Kumar

16-Jun-2023

Dijkstra's algorithm is an algorithm for finding the shortest paths between nodes in a weighted graph. It works by iteratively adding nodes to a set of visited nodes, starting with the source node. For each node that is added to the set, the algorithm examines all of the nodes that are connected to it and updates the shortest path to those nodes if necessary. The algorithm terminates when all of the nodes in the graph have been visited.

Here is the pseudocode for Dijkstra's algorithm:

Code snippet

function dijkstra(graph, source):
    visited = set()
    dist = {}
    for node in graph.nodes:
        dist[node] = float("inf")
    dist[source] = 0

    while visited != graph.nodes:
        node = min(graph.nodes, key=dist.get)
        visited.add(node)
        for neighbor in graph.get_neighbors(node):
            new_dist = dist[node] + graph.get_edge_weight(node, neighbor)
            if new_dist < dist[neighbor]:
                dist[neighbor] = new_dist

    return dist

Here is an explanation of the pseudocode:

  • The visited set keeps track of the nodes that have already been visited.
  • The dist dictionary maps from nodes to their distances from the source node.
  • The min function is used to find the node with the shortest distance that has not yet been visited.
  • The for loop iterates over all of the nodes in the graph.
  • The if statement checks if the node has not already been visited.
  • The new_dist variable is the distance from the current node to the neighbor.
  • The dist[neighbor] variable is the current distance from the source node to the neighbor.
  • The if statement checks if the new distance is shorter than the current distance.
  • If the new distance is shorter, the dist[neighbor] variable is updated with the new distance.
  • The return statement returns the dist dictionary.

Dijkstra's algorithm is a greedy algorithm. This means that it always chooses the node with the shortest distance that has not yet been visited. This guarantees that the algorithm will find the shortest path to the destination node.

Dijkstra's algorithm is a versatile algorithm that can be used to solve a variety of problems. For example, it can be used to find the shortest path between two cities, the shortest route to deliver a package, or the shortest path to connect a network of computers.

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