import java.util.ArrayList;
import java.util.List;
import java.util.Collections;
import java.util.Arrays;
int width = 500;
int height = 500;
int[][] input2={{0,0},{0,32},{32,0},{32,32},{13,13},{13,19},{19,19},{19,13},{16,5},{16,27},{5,16},{27,16}};
int offset=50;
int pointsize=10;
int mult=(width-2*offset)/32;//current run
float max_distance;
int[][] input1 ={{0,0
},{
0,4
},{
4,4
},{
4,0
},{
2,2}};
int crossSign(int[] origin,int[]p1,int p2[]){
  float error=0.0000;
  float[] p11 ={p1[0]-origin[0],p1[1]-origin[1]};
  float[] p21 ={p2[0]-origin[0],p2[1]-origin[1]};
   float cross= p11[0]*p21[1]-p11[1]*p21[0];
   return cross<error?-1:1;
}
boolean noOverlap(ArrayList<int[][]> a,int[] p1,int[] p2){
  for(int[][] line:a)
  {
      if(line[0][0]==p1[0]&&line[0][1]==p1[1]||
          line[1][0]==p1[0]&&line[1][1]==p1[1]||
          line[0][0]==p2[0]&&line[0][1]==p2[1]||
          line[1][0]==p2[0]&&line[1][1]==p2[1]
          ) {
      continue;
      }
    if(crossSign(line[0],line[1],p1)!=crossSign(line[0],line[1],p2)&&
    crossSign(p1,p2,line[0])!=crossSign(p1,p2,line[1]))
      {
        return false;
      }
  }
  return true;
}
int[][][] solveNaive(int[][]input){
  ArrayList<int[][]> c = new ArrayList<int[][]>();
  for(int i =0;i<input.length;i++){
    for(int j=i+1;j<input.length;j++){
      if(noOverlap(c,input[i],input[j]))
         {
           int[][] ct={input[i],input[j]};
          c.add(ct);
         }}}
   int[][][] rv = new int[c.size()][][];
   int i=0;
   for(int[][] line:c){
     rv[i++]=line;
   }
   return rv;
}
int[][][] sollution;
void setup() {
  size(500, 500);
  noStroke();
  List<int[]> l = Arrays.asList(input2);
      Collections.shuffle(l);
      input2=l.toArray(input2);
  sollution=solveNaive(input2);
}
void point(int x,int y){
  x=offset+x*mult;
  y=offset+y*mult;
  fill(color(255,0,0));
  ellipse(x,y,pointsize,pointsize);

}
void line2(int[] p1,int[]p2){
  stroke(color(0));
  int x1=offset+mult*p1[0];
  int y1=offset+mult*p1[1];
  int x2=offset+mult*p2[0];
  int y2=offset+mult*p2[1];
  line(x1,y1,x2,y2);
  noStroke();
}
void draw() {
  background(255,255,255);
   for(int[] a:input2){
     point(a[0],a[1]);
   }
  for(int[][] line:sollution){
  line2(line[0],line[1]);
  }
}