/* check if line ab intersectes with segment cd*/
int check(pt_t a, pt_t b, pt_t c, pt_t d)
{
double tx, ty;
intersec(a, b, c, d, &tx, &ty);
if(online(a, b, c, d)) return 0;
if(onpara(a, b, c, d)) return 0;
if(dcmp(ty - d.y) >= 0 && dcmp(c.y - ty) >= 0) return 1;
return 0;
}
void solve()
{
double maxx, tx, ty;
int flag, i, j, k;
pt_t a, b;
maxx = upper[1].x;
for(i = 1;i <= n; i++)
{
for(j = 1;j <= n; j++)
{
flag = 0;
if(i == j) continue;
a.x = upper[i].x; a.y = upper[i].y;
b.x = botto[j].x; b.y = botto[j].y;
for(k = (i > j ? i : j);k >= 1; k--)
{
if(check(a, b, upper[k], botto[k]) == 0) break;
}
if(k >= 1) continue;
for(k = 1;k <= n; k++)
{
if(check(a, b, upper[k], botto[k]) == 0) break;
}
if(k > n) { flag = 1; break;}
intersec(a, b, upper[k-1], upper[k], &tx, &ty);
if(dcmp(tx - upper[k-1].x) >= 0 && dcmp(upper[k].x - tx) >= 0)
{
if(maxx + eps < tx) maxx = tx;
}
intersec(a, b, botto[k-1], botto[k], &tx, &ty);
if(dcmp(tx - botto[k-1].x) >= 0 && dcmp(botto[k].x - tx) >= 0)
{
if(maxx + eps < tx) maxx = tx;
}
}
if(flag) break;
}
if(flag) printf("Through all the pipe.\n");
else printf("%0.2lf\n", maxx);
}
int main() {
int a[100], b[100], c[100], i, j, n;
printf("qual o numero de conjuntos? ");
scanf("%d", &n);
lerVetor(a);
for (i = 1; i < n; i++) {
lerVetor(b);
intersec(a, b, c);
memcpy(&a, &c, sizeof a);
}
printf("\na interseccao dos conjuntos é ");
imprimirVetor(c);
return 0;
}
