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dijkstra.c
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dijkstra.c
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#include<stdio.h>
#include<stdlib.h>
# define MAX 10
# define INF 99999
void dijkstra(int graph[MAX][MAX], int v, int start);
int main()
{
int graph[MAX][MAX],v, start;
int i, j;
printf("Enter number of vertices (v): ");
scanf("%d",&v);
printf("Enter the graph nodes: \n");
for(i=0; i<v; i++)
{
for(j=0; j<v; j++)
{
scanf("%d",&graph[i][j]);
}
}
printf("Enter starting node: \n");
scanf("%d",&start);
dijkstra(graph, v, start);
}
void dijkstra(int graph[MAX][MAX], int v, int start)
{
int cost[MAX][MAX]; //The edge weights, INF if the node is not directly linked to the node being processed (user will enter 0 in that case)
int dist[MAX]; //Stores the shortest distance required to reach from the start node to that node
int processed[MAX]; //Hold true or false, whether a node has been processed(true) or not(false)
int prev[MAX]; // Stores the node previous to the current node (will be used to make the graph of shortest distance)
int i, j, count, min_dist, next;
//The edge weights array
for(i=0; i<v; i++)
{
for(j=0; j<v; j++)
{
if(graph[i][j]==0)
{
cost[i][j]=INF;
}
else
{
cost[i][j]=graph[i][j];
}
}
}
// The prev node and processed array
for(i=0; i<v; i++)
{
dist[i] = cost[start][i];
prev[i] = start;
processed[i] = 0;
}
dist[start] = 0;
processed[start] = 1;
count = 1;
while(count < (v-1))
{
min_dist = INF;
for(i = 0; i < v; i++)
{
if(dist[i]<min_dist && !processed[i])
{
min_dist = dist[i];
next=i;
}
}
processed[next] = 1;
for(i = 0; i < v; i++)
{
if(!processed[i])
{
if((min_dist + cost[next][i]) < dist[i])
{
dist[i]= (min_dist + cost[next][i]);
prev[i]=next;
}
}
}
count++;
}
for(i = 0; i < v; i++)
{
if(i != start)
{
printf("The distance of %d from %d is %d", i, start, dist[i]);
printf("Path is %d",i);
j=i;
do
{
j = prev[j];
printf("->%d", j);
}while(j != start);
}
printf("\n");
}
}