Segments intersection

#include <cstdio>
#include <algorithm>

int vmul(int x0, int y0, int x1, int y1, int x2, int y2) {
  x1 -= x0;
  y1 -= y0;
  x2 -= x0;
  y2 -= y0;
  int c = x1 * y2 - x2 * y1;
  return c < 0 ? -1 : c > 0 ? 1 : 0;
}

int main() {
  freopen("segments.in", "r", stdin);
  freopen("segments.out", "w", stdout);
  int x1, y1, x2, y2, x3, y3, x4, y4;
  scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
  scanf("%d%d%d%d", &x3, &y3, &x4, &y4);
  int v1 = vmul(x1, y1, x3, y3, x4, y4);
  int v2 = vmul(x2, y2, x3, y3, x4, y4);
  int u1 = vmul(x3, y3, x1, y1, x2, y2);
  int u2 = vmul(x4, y4, x1, y1, x2, y2);
  if (v1 == 0 && v2 == 0 && u1 == 0 && u2 == 0) {
    int lx = std::max(std::min(x1, x2), std::min(x3, x4));
    int rx = std::min(std::max(x1, x2), std::max(x3, x4));
    int ly = std::max(std::min(y1, y2), std::min(y3, y4));
    int ry = std::min(std::max(y1, y2), std::max(y3, y4));
    if (lx > rx || ly > ry)
      puts("Empty");
    else {
      if (lx < rx || ly < ry) {
        if (vmul(lx, ly, x1, y1, x2, y2) != 0)
          std::swap(ly, ry);
        printf("%d %d\n%d %d\n", lx, ly, rx, ry);
      } else {
        printf("%d %d\n", lx, ly);
      }
    }
  } else if (v1 != v2 && u1 != u2) {
    double a1 = y2 - y1;
    double b1 = x1 - x2;
    double c1 = -x1 * a1 - y1 * b1;
    double a2 = y4 - y3;
    double b2 = x3 - x4;
    double c2 = -x3 * a2 - y3 * b2;
    double z = a1 * b2 - b1 * a2;
    printf("%.17lf %.17lf\n", (b1 * c2 - c1 * b2) / z, (c1 * a2 - a1 * c2) / z);
  } else {
    puts("Empty");
  }
}