Dijstra_with_negative_edge.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
 
struct Edge
{
   //This structure tales the elements of edge like starting point, ending point and weight
    int source, destination, weight;
};
 

struct Graph
{
    int V, E;

 
    struct Edge* edge;

};
 
struct Graph* createGraph(int V, int E)
{
    struct Graph* graph = (struct Graph*) malloc( sizeof(struct Graph));

 
    graph->V = V;   //assigning the values taken from user
 
    graph->E = E;
 
    graph->edge = (struct Edge*) malloc( graph->E * sizeof( struct Edge ) );

 
    return graph;
}
 
void FinalSolution(int dist[], int n)
{
//To print final shortest path
    printf("\nVertex\tDistance from Source Vertex\n");
    int i;
 
    for (i = 0; i < n; ++i){
printf("%d \t\t %d\n", i, dist[i]);
}
}
 
void dijkstra_negative(struct Graph* graph, int source) 
{
    int V = graph->V;
 
    int E = graph->E;
 
    int StoreDistance[V];
 
    int i,j;
 
    //  we initialize all distance to infinity except source.
// We assign source distance as 0(zero)
 
    for (i = 0; i < V; i++)
        StoreDistance[i] = INT_MAX;
 
    StoreDistance[source] = 0;
 
    //The shortest path of graph that contain V vertices has  V-1 relaxations
    for (i = 1; i <= V-1; i++)
    {
        for (j = 0; j < E; j++)
        {
            int u = graph->edge[j].source;
 
            int v = graph->edge[j].destination;
 
            int weight = graph->edge[j].weight;
 
            if (StoreDistance[u] + weight < StoreDistance[v]) 
                StoreDistance[v] = StoreDistance[u] + weight;
        }
    }
 
    
 
    // If we get a shorter path, then there is a negative edge cycle.
    for (i = 0; i < E; i++)
    {  
        int u = graph->edge[i].source;
 
        int v = graph->edge[i].destination;
 
        int weight = graph->edge[i].weight;
 
        if (StoreDistance[u] + weight < StoreDistance[v])
            printf("This graph contains negative edge cycle\n");
    }
 
    FinalSolution(StoreDistance, V);
 
    return;
}
 
int main()
{
    int V,E,S;  //V = no.of Vertices, E = no.of Edges, S is source vertex 
    
    printf("Suvarna Lakshmi P \n");
    printf("20BDS0322\n");
    
 
printf("Enter number of vertices in graph\n");
    scanf("%d",&V);
 
printf("Enter number of edges in graph\n");
    scanf("%d",&E);
 
printf("Enter your source vertex number\n");
scanf("%d",&S);
 
    struct Graph* graph = createGraph(V, E);    //calling the function to allocate space to  vertices and edges
 
    int i;
    for(i=0;i<E;i++){
        printf("\nEnter edge %d properties Source, destination, weight respectively\n",i+1);
        scanf("%d",&graph->edge[i].source);
        scanf("%d",&graph->edge[i].destination);
        scanf("%d",&graph->edge[i].weight);
    }
 
    dijkstra_negative(graph, S);
//passing created graph and source vertex to dijkstra_negative function
 
    return 0;
}