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## Discussion of Problem 1103. Pencils and Circles

How to solve this problem without long arithmetic?
Posted by Felix_Mate 10 Aug 2017 16:38
If i use double -> big error
If i use long long -> overflow
now i got Runtime error on java. Where I am wrong? I think my function Less is bad but I can't find mistake.

My code:
import java.math.*;
import java.util.*;

public class BigNumbers
{
final int tmax=100;
MathContext mc = new MathContext(tmax);

final int nmax=5005;

static int Pox[], Poy[], id[];
static BigDecimal Px[], Py[];
static int n, left;

public static boolean Less(BigDecimal x1, BigDecimal y1, BigDecimal x2, BigDecimal y2)
{
return (y1.compareTo(BigDecimal.ZERO)!=-1) && (y2.compareTo(BigDecimal.ZERO)==1) &&
((y1.multiply(x2)).compareTo(x1.multiply(y2))==-1) ||
(y1.compareTo(BigDecimal.ZERO)==-1) && ((y2.compareTo(BigDecimal.ZERO)!=-1)) ||
((x1.multiply(y2)).compareTo(x2.multiply(y1))==1);
}

public static BigDecimal modul2(BigDecimal x, BigDecimal y)
{
}

public static void QSort(int L, int R)
{
int m=(L+R)/2;
int i=L;
int j=R;

while(i<=j)
{
while(Less(Px[i],Py[i],Px[m],Py[m])) i++;
while(!Less(Px[j],Py[j],Px[m],Py[m]) && j!=m) j--;
if(i<=j)
{
BigDecimal Y=Px[i];
Px[i]=Px[j];
Px[j]=Y;
Y=Py[i];
Py[i]=Py[j];
Py[j]=Y;
int y=id[i];
id[i]=id[j];
id[j]=y;
i++;
j--;
}
}
if(L<j) QSort(L, j);
if(i<R) QSort(i, R);
}

public static void main(String args[])
{
Scanner sc=new Scanner(System.in);

n=sc.nextInt();

Pox=new int[n+1];
Poy=new int[n+1];
id=new int[n+1];
Px=new BigDecimal[n+1];
Py=new BigDecimal[n+1];

for(int i=1;i<=n;i++)
{
int x, y;
x=sc.nextInt();
y=sc.nextInt();
Pox[i]=x;
Poy[i]=y;
}

System.out.println(Pox[1]+" "+Poy[1]);

for(int i=1;i<=n-1;i++)
{
BigDecimal x=BigDecimal.valueOf(Pox[i+1]-Pox[1]);
BigDecimal y=BigDecimal.valueOf(Poy[i+1]-Poy[1]);
Px[i]=x.divide(modul2(x,y));
Py[i]=y.divide(modul2(x,y));
id[i]=i+1;
}

left=1;
for(int i=2;i<=n-1;i++)
if(Px[left].compareTo(Px[i])==1 || Px[left].compareTo(Px[i])==0 &&
Py[left].compareTo(Py[i])==1) left=i;

System.out.println(Pox[id[left]]+" "+Poy[id[left]]);

for(int i=1;i<=n-1;i++)
{
Px[i]=Px[i].subtract(Px[left]);
Py[i]=Py[i].subtract(Py[left]);
}

for(int i=left;i<=n-2;i++)
{
Px[i]=Px[i+1];
Py[i]=Py[i+1];
}

QSort(1,n-2);
System.out.print(Pox[id[(n-1)/2]]+" "+Poy[id[(n-1)/2]]);
}
}