C PROGRAMMING Implement dijkstras alorithm Check that the Graph graph, and starting node, id, are valid • Create the set S containing all the networks (vertices) except the source node (you might want to use an array for this. • Create an array to represent the table D and initialise it with the weights of the edges from the source node, or infinity if no edge exists. You should use the constant DBL_MAX to represent infinity. • Create an array to represent the table R and initialise it with the next hops if an edge exists from the source, or 0 otherwise. • Then repeatedly follow the remaining rules of Dijkstra’s algorithm, updating the values in D and R until S is empty. • Each of the values required to complete the above can be found by calling the various functions (get_vertices(), get_edge(), edge_destination(), edge_weight(), etc.) in the supplied graph library. • Once Dijkstra’s algorithm has run, you will need to create the routing table to be returned by allocating enough memory for the required number of Path structures and filling each entry of the array. • Finally, you should free() any unused memory you have allocated, set *pnEntries to the correct value, and return the pointer to the routing table you’ve just filled in (obviously, you shouldn’t free that!) using the below as a starting point: /* * dijkstra.c * ProgrammingPortfolio * */ #include #include #include #include #include "graph.h" #include "dijkstra.h" /* find shortest paths between source node id and all other nodes in graph. */ /* upon success, returns an array containing a table of shortest paths. */ /* return NULL if *graph is uninitialised or an error occurs. */ /* each entry of the table array should be a Path */ /* structure containing the path information for the shortest path between */ /* the source node and every node in the graph. If no path exists to a */ /* particular desination node, then next should be set to -1 and weight */ /* to DBL_MAX in the Path structure for this node */ Path *dijkstra(Graph *graph, int id, int *pnEntries) { Path *table = NULL; /* Insert your implementation of Dijkstra's algorithm here */ return table; }

C PROGRAMMING

Implement dijkstras alorithm

Check that the Graph graph, and starting node, id, are valid
• Create the set S containing all the networks (vertices) except the source node (you might want
to use an array for this.
• Create an array to represent the table D and initialise it with the weights of the edges from the
source node, or infinity if no edge exists. You should use the constant DBL_MAX to represent
infinity.
• Create an array to represent the table R and initialise it with the next hops if an edge exists
from the source, or 0 otherwise.
• Then repeatedly follow the remaining rules of Dijkstra’s algorithm, updating the values in D and
R until S is empty.
• Each of the values required to complete the above can be found by calling the various
functions (get_vertices(), get_edge(), edge_destination(), edge_weight(), etc.)
in the supplied graph library.
• Once Dijkstra’s algorithm has run, you will need to create the routing table to be returned by
allocating enough memory for the required number of Path structures and filling each entry of
the array.
• Finally, you should free() any unused memory you have allocated, set *pnEntries to the
correct value, and return the pointer to the routing table you’ve just filled in (obviously, you
shouldn’t free that!)

using the below as a starting point:

/*
* dijkstra.c
* ProgrammingPortfolio
*
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <float.h>
#include "graph.h"
#include "dijkstra.h"

/* find shortest paths between source node id and all other nodes in graph. */
/* upon success, returns an array containing a table of shortest paths. */
/* return NULL if *graph is uninitialised or an error occurs. */
/* each entry of the table array should be a Path */
/* structure containing the path information for the shortest path between */
/* the source node and every node in the graph. If no path exists to a */
/* particular desination node, then next should be set to -1 and weight */
/* to DBL_MAX in the Path structure for this node */
Path *dijkstra(Graph *graph, int id, int *pnEntries)
{
Path *table = NULL;

/* Insert your implementation of Dijkstra's algorithm here */

return table;
}