Question

firstly, i write this code:

int X, Y;
for (i=0; i<N; i++)
{
    printf("Enter X and Y: ");
    scanf("%d %d", &X, &Y);
}

int A[X][Y];

for (int i=0;i<X;i++){
    for (int j=0;j<Y;j++){
        printf("A[i][j]:");
        scanf("%d", &A[i][j]);
    }
}

but, I have trouble with the calculation I couldn’t improve it.

Answer 1

What you appear to be looking for is the furthest neighbour between points. Writing a brute force solution is trivial, just compare distances between every possible pair of points. As per the link, far better solutions exist.

Edit: Distance between two points is

double distance(double x1,double y1,double x2, double y2)
{
  return sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}