// Input a positive integer n from the user and then input n vectors of size 3.
// The memory for storing these n vectors of size 3 must be allocated dynamically
// and together.
/*Now, compute the pairwise distance among these n vectors and store them in a
nxn matrix. The memory for this matrix should also be stored dynamically*/

//Author: rahule@iitk.ac.in
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
float dist(int x1,int x2,int x3,int y1,int y2,int y3);		//calculates the distance between the points (x1,x2,x3, y1,y2,y3)
int main()
{
  int i,j,n,*a;
  float *d;
  printf("\nEnter the number of vectors :");
  scanf("%d",&n);
  a=(int *)malloc(n*3*sizeof(int));	//allocating space to store the vectors.(imagine it as a a[n][3] arrray
  d=(float *)malloc(n*n*sizeof(float));	//allocating space to store the distance calculated.(nxn)
  for(i=0;i<n;i++)		//enterind the vector i
  {
    printf("\nEnter vector %d:",i+1);
    scanf("%d",a+i*3);
    scanf("%d",a+i*3+1);
    scanf("%d",a+i*3+2);
  }
  for(i=0;i<n;i++)
    for(j=0;j<n;j++)
    {
      *(d+i*n+j)=dist(*(a+i*3),*(a+i*3+1),*(a+i*3+2),  *(a+j*3),*(a+j*3+1),*(a+j*3+2));		//equals to d[i,j]=dist(a[i][1],a[i][2],a[i][3].a[j][1],a[j][2],a[j][3])
    }
    
    //printing the distances
    printf("\nThe distance matrix is as follows");
    for(i=0;i<n;i++)
    {
      printf("\n");
      for(j=0;j<n;j++)
      {
	printf("  %f",*(d+i*n+j));	//similar to printing d[i][j]
      }
    }
    printf("\n");
}

float dist(int x1,int x2,int x3,int y1,int y2,int y3)
//calculates the distance between the points (x1,x2,x3, y1,y2,y3)
{
  float d;
  
  d=sqrt((float)((y1-x1)*(y1-x1)+(y2-x2)*(y2-x2)+(y3-x3)*(y3-x3)));
  return(d);
}