Graph : Shortest Path Computation using Warshall's Algorithm

/* WARSHALL.C */

# include
# define size 10

int a [size][size];
int p [size][size];
int i,k,j;
int n;

void Input ();
void Warshall ();
void Output ();

/* Input function */

void Input()
{
 printf("\n Input the number of vertices: ");
 scanf("%d", &n);
 printf("\n Input adjency matrix\n");
 for ( i = 0; i < n; i++)
 {
  for ( j = 0; j < n; j++)
  {
   scanf("%d", &a[i][j]);
  }
  printf("\n");
 }
 printf("\n Adjency matrix \n");
 for ( i = 0; i < n; i++)
 {
  for ( j = 0; j < n; j++)
  {
   printf(" %d", a[i][j]);
  }
  printf("\n");
 }
}

/* Output function */

void   Output()
{
 for ( i = 0; i < n; i++)
 {
  for ( j = 0; j < n; j++)
  {
   printf("  %d", p [i][j]);
  }
  printf("\n");
 }
}

/* Shortest path function */

void  Warshall ()
{
 /* Initialization of matrix m */

 for ( i = 0; i < n; i++)
 {
  for ( j = 0; j < n; j++)
  {
   if (a[i][j] == 0)
    p [i][j] = 0;
   else
    p[i][j] = 1;
  }
 }

 /* Shortest Path evaluation start from here */

 for ( k = 0; k < n; k++)
 {
  for ( i = 0; i < n; i++)
  {
   for ( j = 0; j < n; j++)
   {
    p[i][j] = p[i][j] | ( p[i][k] & p[k][j]);
   }
  }
 }
}

/* Function main */

void main()
{
 Input ();
 Warshall ();
 printf("\n Path matrix:\n");
 Output ();
}