Thread: Longest envelope of the set of points

I want to find the longest envelope of the set of points, means that the longest line that circumvent each point in the set I have input, and then calculate its length. My idea is to find the edge point in every line, there are 3 case:
1. no points - go to the next line,
2. 1 point - put it into array twice,
3, 2 or more points, then find the most on the left and the most on the right.
I intend to start putting them into array at the ery top of, this time input coordinates, then proceed left, so if there is only one point in a line and "m" is a number of non-empty lines, its coordinates would be Arr[i].x,Arr[i].y and
Arr[i+m].x,Arr[i+m].y
My input was
3
1 2
3 4
5 6
The program crashed. I tried working with debugger but it was of no help, since I do not fulluy understand the way the debugger works.
I put my code.
thanks for help in advance.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <ctime>
#include <math.h>
typedef struct {
    int x;
    int y;
} point;
int ScanningNumberOfPoints();
void GeneratingPoints(int n, point tab[200]);
void FindingExtremePositions(point tab[200], int n, point Arr[1000], int m);     // two points in each line; one most on right, and one most on left
void Distance (point Arr1[1000], int n, int m);
 
int main()
{
int m=0;   // size of an array of extreme points
point tab[200];     // array of all coordinates
point Arr[1000];   //array of extreme points   
int n = ScanningNumberOfPoints();   // number of randomly generated points
GeneratingPoints(n, tab);
FindingExtremePositions(tab, n, Arr, m);
Distance (Arr, n, m);
}
int ScanningNumberOfPoints()
{
int n;
printf("input how many points you'd like to see:\n");
scanf("%d", &n);
return n;
} 
 
void GeneratingPoints(int n, point tab[200])
{
 for(int i =0; i < n; i++)
  {
   scanf("%d", &tab[i].x);
   scanf("%d", &tab[i].y);
  }
}
 
void FindingExtremePositions( point tab[200], int n, point Arr[1000], int m)
{
int max=0;
int min=1000;
int licznik = 0;
int licznik1 = 0;
  //half of the points
int a; //The highest point
int d=0;
int numerpodwojnejlinii;
int zapamietajmaxwpodwojnejlinii=0;
int zapamietajminwpodwojnejlinii =111;
for(int i=0;i<50;i++)
{
 for(int y=0;y<50;y++)
 {
  if(tab[y].x!=i) //HOW MANY POINTS ARE IN ONE LINE 
  {
   m++; // NUMBER OF EMPTY LINES
  }  
 }
}
for(int i=0;i<n;i++)
{
 if(tab[i].y>max)
 {
  max=tab[i].y;
  a=i;
 }
}

for(int i=0;i<50;i++)
{
 for(int a=0;a<50;a++)
 {
  if(tab[a].y==i) //HOW MANY POINTS ARE IN ONE LINE 
  {
   d++; 
   numerpodwojnejlinii=i;
  }  
 }
 if(d==0)
 {}
 else
 if(d==1)
 {
 Arr[i].x=tab[i].x;
 Arr[i].y=tab[i].y;
 Arr[i+m].x=tab[i].x;
 Arr[i+m].y=tab[i].y;  
 }
 if(d>=2)
 {
  for(int r=0;r<n;r++)
  {
   if(tab[r].y==numerpodwojnejlinii)
    {
     if(tab[r].x>max)
     {
     max=tab[r].x; 
     zapamietajmaxwpodwojnejlinii=r;
     }
     if(tab[r].x<min)
     {
     min=tab[r].x; 
     zapamietajminwpodwojnejlinii=r;
     }     
    }
  }
  Arr[i].x=tab[zapamietajmaxwpodwojnejlinii].x;
  Arr[i].y=tab[zapamietajmaxwpodwojnejlinii].y;
  Arr[i+m].x=tab[zapamietajminwpodwojnejlinii].x;
  Arr[i+m].y=tab[zapamietajminwpodwojnejlinii].y;
  //numerpodwojnejlinii=0;
  //zapamietajmaxwpodwojnejlinii=0;
  //zapamietajminwpodwojnejlinii=110; 
  //max=0;
 // min=100;
 }
}
}
 
void Distance (point Arr[1000], int n, int m)
{
 double sum=0;
 for(int i = 0;i<2*m;i++)
 {
  sum+=sqrt(pow((Arr[i+1].x-Arr[i].x),2)+pow((Arr[i+1].y-Arr[i].y),2));
 }
 sum=sum+sqrt(pow((Arr[2*m-1].x-Arr[0].x),2)+pow((Arr[2*m-1].y-Arr[0].y),2));
 printf("%lf\n", sum);
}