/* intersectia a n segmente  */

#include <stdio.h>
#include <conio.h>

struct segment {
  int X1,Y1,X2,Y2;

} S [100];

float a1,a2,b1,b2,c1,c2;
  
int main(void) {
     int n,i,j;
     printf("n=");scanf("%d",&n);
     for(i=1;i<=n;i++) {
         printf("\nSegmentul S%d[X1,Y1][X2,Y2]",i);
         printf("\nX1=");scanf("%d",&S[i].X1);
         printf("\nY1=");scanf("%d",&S[i].Y1);
         printf("\nX2=");scanf("%d",&S[i].X2);
         printf("\nY2=");scanf("%d",&S[i].Y2); 
         }
     for(i=1;i<=n;i++) {
        for(j=1;j<=n;j++) {
        if(i!=j){ 
                 a1=(S[i].Y2-S[i].Y1)/(S[i].X2-S[i].X1);
                 a2=(S[j].Y2-S[j].Y1)/(S[j].X2-S[j].X1);
                 b1=S[i].Y1-a1*S[i].X1;
                 b2=S[j].Y1-a2*S[j].X1;
                 c1= -(b1-b2)/(a1-a2);
                 c2= b1+a1*c1;
                   if ( ( (S[i].X1-c1)*(c1-S[i].X2)>=0) && ((S[j].X1-c1)*(c1-S[j].X2)>=0) && ((S[i].Y1-c2)*(c2-S[i].Y2)>=0) && ((S[j].Y1-c2)*(c2-S[j].Y2)>=0) ) 
                      printf("\nS%d se intersecteaza cu S%d",i,j);
                                    else printf("\nS%d nu se intersecteaza cu S%d",i,j);
                 
                    }
        }
     }
     for(i=1;i<=n;i++) {
         printf("\nSegmentul S%d[%d,%d][%d,%d]",i,S[i].X1,S[i].Y1,S[i].X2,S[i].Y2);
         }
     getch();
     }