/*Program for Modified Warshall's algorithm to find shoretst path matrix */
#include<stdio.h>
#define infinity 9999
#define MAX 20
main()
{
int i,j,k,n;
int adj[MAX][MAX],path[MAX][MAX];
printf("Enter number of vertices : ");
scanf("%d",&n);
printf("Enter weighted matrix :\n");
for(i=0;i<n;i++)
for(j=0;j<n;j++)
scanf("%d",&adj[i][j]);
printf("Weighted matrix is :\n");
display(adj,n);
/*Replace all zero entries of adjacency matrix with infinity*/
for(i=0;i<n;i++)
for(j=0;j<n;j++)
if(adj[i][j]==0)
path[i][j]=infinity;
else
path[i][j]=adj[i][j];
for(k=0;k<n;k++)
{
printf("Q%d is :\n",k);
display(path,n);
for(i=0;i<n;i++)
for(j=0;j<n;j++)
path[i][j]=minimum( path[i][j] , path[i][k]+path[k][j] );
}
printf("Shortest path matrix Q%d is :\n",k);
display(path,n);
}/*End of main() */
minimum(int a,int b)
{
if(a<=b)
return a;
else
return b;
}/*End of minimum()*/
display(int matrix[MAX][MAX],int n )
{
int i,j;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
printf("%7d",matrix[i][j]);
printf("\n");
}
}/*End of display()*/