diskajstra_full_implementation_copy_from_githhub.c

// A C / C++ program for Dijkstra's single source shortest path algorithm.
// The program is for linkedlist representation of the graph
#include <stdio.h>
#include <limits.h>
#include <iostream>
#include <vector>
#include "graph_class.h"
#include <fstream>
using namespace std;
// Number of vertices in the graph
#define V 9
// A utility function to find the vertex with minimum distance value, from
// the set of vertices not yet included in shortest path tree
int minDistance(int dist[], bool sptSet[])
{
// Initialize min value
int min = INT_MAX, min_index;
for (int v = 0; v < V; v++)
if (sptSet[v] == false && dist[v] <= min)
min = dist[v], min_index = v;
return min_index;
}
// A utility function to print the constructed distance array
void printSolution(int dist[], int n)
{
printf("Vertex Distance from Source\n");
for (int i = 0; i < V; i++)
printf("%d \t\t %d\n", i, dist[i]);
}
void printPath(int (&path)[V], int i)
{
printf("\t %d", i);
if(i == 0) return;
else
printPath(path, path[i]);
}
int findWeight(GRAPH graph, int x, int y) // find weight of edge x-y
{
struct edgenode *p = graph.g.edges[x];
while(p!=NULL)
{
if(p->y == y) return p->weight;
p = p->next;
}
printf("Error with finding weight of edge %d - %d", x, y);
return 0;
}
// Function that checks whether an edge exists
bool hasEdge(GRAPH graph, int x, int y)
{
cout<<"Checking edge "<<x<<"-"<<y<<endl;
struct edgenode *p = graph.g.edges[x];
while(p!=NULL)
{
if(p->y == y) return true;
p = p->next;
}
cout<<"No edge"<<endl;
return false;
}
// Funtion that implements Dijkstra's single source shortest path algorithm
// for a graph represented using adjacency matrix representation
void dijkstra(GRAPH graph, int src)
{
int dist[V]; // The output array. dist[i] will hold the shortest
// distance from src to i
bool sptSet[V]; // sptSet[i] will true if vertex i is included in shortest
// path tree or shortest distance from src to i is finalized
int path[V];
path[0] = 0;
// Initialize all distances as INFINITE and stpSet[] as false
for (int i = 0; i < V; i++)
dist[i] = INT_MAX, sptSet[i] = false;
// Distance of source vertex from itself is always 0
dist[src] = 0;
// Find shortest path for all vertices
for (int count = 0; count < V-1; count++)
{
// Pick the minimum distance vertex from the set of vertices not
// yet processed. u is always equal to src in first iteration.
int u = minDistance(dist, sptSet);
// Mark the picked vertex as processed
sptSet[u] = true;
// Update dist value of the adjacent vertices of the picked vertex.
for (int v = 0; v < V; v++)
// Update dist[v] only if is not in sptSet, there is an edge from
// u to v, and total weight of path from src to v through u is
// smaller than current value of dist[v]
if (!sptSet[v] && hasEdge(graph, u, v) && dist[u] != INT_MAX
&& dist[u]+ findWeight(graph, u, v) < dist[v])
{
dist[v] = dist[u] + findWeight(graph, u, v);
cout<<"line 93"<<endl;
path[v] = u;
}
// print the constructed distance array
printSolution(dist, V);
}
printf("Paths are: ");
for(int i = 0; i < V; i++)
{
printf("\nPath from 0 to %d : \t", i);
printPath(path, i);
}
printf("\n");
}
// driver program to test above function
int main()
{
/* Let us create the example graph discussed above */
GRAPH gh(9, 0);
gh.readGraph("graph.txt");
cout <<"Input graph is: "<<endl;
gh.printGraph();
cout <<"Result: "<<endl;
dijkstra(gh, 0);
return 0;
}