// All pairs shortest paths problem
// Sequential version
// Written by M. Eggen

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define infinity 1000000

int GetSize(char *filename);
int **Allocate(int n);
void Fill(int **adjmat, int n, char *filename);
void Display(int **adjmat, int n);
int **Floyd(int **adjmat, int n);
int min(int a, int b);

main(int argc, char **argv)
{	int 
		**adjmat,
		**shortpath,
		n;
	char 
		filename[20];

// get the name of the file from command line or user
	if (argc != 2)
	{
		printf("Please enter name of file containing adjacency matrix: ");
		scanf("%s",filename);
	}
	else
		strcpy(filename, argv[1]);

	n = GetSize(filename);
	printf("%d by %d\n",n,n);
	adjmat = Allocate(n);
	Fill(adjmat,n,filename);
	Display(adjmat,n);
	getchar();
	shortpath = Floyd(adjmat,n);
	Display(shortpath,n);
}
int **Floyd(int **adjmat, int n)
{	int **I[20];
	int i,j,k;
	for(i=0;i<20;i++)
	{	I[i] = Allocate(n);
	}
/******************* for boolean matrices **************************
	for(i=0;i<n;i++)
	{	for(j=0;j<n;j++)
		{	if (adjmat[i][j] == 1)	
				I[0][i][j] = 1;
			else
				I[0][i][j] = infinity;
		}
	}
**********************************************************************/
	for(i=0;i<n;i++)
	{	for(j=0;j<n;j++)
		{	if (adjmat[i][j] != 0)	
				I[0][i][j] = adjmat[i][j];
			else
				I[0][i][j] = infinity;
		}
	}
	for(i=0;i<n;i++)
		I[0][i][i] = 0;
	Display(I[0],n);
	getchar();

// These are the main loops
// I will temporarily display all the intermediate matrices

	for(k=0;k<n-1;k++)
	{	for(i=0;i<n;i++)
		{	for(j=0;j<n;j++)
			{	I[k+1][i][j] = min(I[k][i][j], I[k][i][k] + I[k][k][j]);
			}
		}
		Display(I[k],n);
		getchar();
	}
	return I[n-1];
}
void Display(int **adjmat, int n)
{	int i,j;
	for(i=0;i<n;i++)
	{	for(j=0;j<n;j++)
		{	if (adjmat[i][j] == infinity)
				printf("%8c",169);
			else
				printf("%8d",adjmat[i][j]);
		}
		printf("\n");
	}
	printf("\n");
}
void Fill(int **adjmat, int n, char *filename)
{	FILE *filepointer;
	int i,j;
	filepointer = fopen(filename,"r");
	for(i=0;i<n;i++)
		for(j=0;j<n;j++)
			fscanf(filepointer,"%d",&adjmat[i][j]);
	fclose(filepointer);
}
int **Allocate(int n)
{	int 
		i,
		**temp;

	temp = (int **)malloc(n*sizeof(int *));
	if (!temp)
	{	printf("matrix allocation failed\n");
		exit(2);
	}
	for(i=0;i<n;i++)
		temp[i] = (int *)malloc(n*sizeof(int));
	return temp;
}
int GetSize(char *filename)
{	FILE 
		*filepointer;
	int
		x,
		n;

	filepointer = fopen(filename,"r");
	if (!filepointer)
	{	printf("The file %s doesn't exist\n",filename);
		exit(1);
	}
	n = 0;
	fscanf(filepointer,"%d",&x);
	while (!feof(filepointer))
	{	n++;
		fscanf(filepointer,"%d",&x);
	}
	fclose(filepointer);
	n = (int)sqrt(n);
	return n;
}
int min(int a, int b)
{	if (a <= b)
		return a;
	return b;
}