#include<stdio.h>
#include<string.h>
int main()
{
int count,src_router,i,j,k,w,v,min;
int cost_matrix[100][100],dist[100],last[100];
int flag[100];
printf("\n Enter the no of routers");
scanf("%d",&count);
printf("\n Enter the cost matrix values:");
for(i=0;i<count;i++)
{
for(j=0;j<count;j++)
{
printf("\n%d->%d:",i,j);
scanf("%d",&cost_matrix[i][j]);
if(cost_matrix[i][j]<0)cost_matrix[i][j]=1000;
}}
printf("\n Enter the source router:");
scanf("%d",&src_router);
for(v=0;v<count;v++)
{
flag[v]=0;
last[v]=src_router;
dist[v]=cost_matrix[src_router][v];
}
flag[src_router]=1;
for(i=0;i<count;i++)
{
min=1000;
for(w=0;w<count;w++)
{
if(!flag[w])
if(dist[w]<min)
{
v=w;
min=dist[w];
}}
flag[v]=1;
for(w=0;w<count;w++)
{
if(!flag[w])
if(min+cost_matrix[v][w]<dist[w])
{
dist[w]=min+cost_matrix[v][w];
last[w]=v;
}
}}
for(i=0;i<count;i++)
{
printf("\n%d==>%d:Path taken:%d",src_router,i,i);
w=i;
while(w!=src_router)
{
printf("\n<--%d",last[w]);w=last[w];
}
printf("\n Shortest path cost:%d",dist[i]);
}
}

Output:
"open.c" 65L, 1011C written[ME04@TELNET ~]$ cc open.c
[ME04@TELNET ~]$ ./a.out
Enter the no of routers 4
Enter the cost matrix values
0->0:1
0->1:4
0->2:6
0->3:8
1->0:4
1->1:6
1->2:5
1->3:9
2->0:1
2->1:3
2->2:2
2->3:0
3->0:4
3->1:2
3->2:6
3->3:8
Enter the source router:3
3==>0:
Path taken:0<--3Shortest path cost:4

3==>1:Path taken:1<--3
Shortest path cost:2
3==>2:
Path taken:2<--3
Shortest path cost:6
3==>3:
Path taken:3
Shortest path cost:8