判断线段相交并求交点

const double precision = 1e-6;const double inf = (1<<30);const int maxn = 1e6+10;int n;struct Tpoint{    double x;    double y;    Tpoint(double x = 0, double y = 0) : x(x) , y(y) { }    void print(){        printf(" (%.3f,%.3f) \n",x,y);    }}l11,l12,l21,l22,l31,l32,l41,l42,bl11,bl12,bl21,bl22,bl31,bl32,bl41,bl42;Tpoint operator + (Tpoint A, Tpoint B) { return Tpoint(A.x+B.x, A.y+B.y); }Tpoint operator - (Tpoint A, Tpoint B) { return Tpoint(A.x-B.x, A.y-B.y); }Tpoint operator * (Tpoint A, double p) { return Tpoint(A.x*p, A.y*p); }Tpoint operator / (Tpoint A, double p) { return Tpoint(A.x/p, A.y/p); }struct Tline{    Tpoint a,b;    Tline(Tpoint x,Tpoint y):a(x),b(y){};};Tpoint bzx,bys,szx,sys,a[maxn],b[maxn];int line[maxn];pii check[5],inter[5];pdi ans[maxn*4];int anscnt = 0;double crossprod(Tpoint a,Tpoint b,Tpoint c){  return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);}bool intersection(Tpoint a,Tpoint b,Tpoint c,Tpoint d){  if(max(a.x,b.x)>=min(c.x,d.x) &&     max(c.x,d.x)>=min(a.x,b.x) &&     max(a.y,b.y)>=min(c.y,d.y) &&     max(c.y,d.y)>=min(a.y,b.y) &&     crossprod(a,b,c)*crossprod(a,b,d)<=0 &&     crossprod(c,d,a)*crossprod(c,d,b)<=0)return 1;  return 0;}double det(Tpoint a,Tpoint b){    return a.x*b.y-a.y*b.x;}pii GetLineIntersection(Tpoint A, Tpoint B, Tpoint C, Tpoint D) {    Tline a = Tline(A,B);    Tline b = Tline(C,D);    double s1 = det(a.a-b.a,b.b-b.a);    double s2 = det(a.b-b.a,b.b-b.a);    Tpoint res ;    res = (a.b*s1-a.a*s2)/(s1-s2);    return make_pair(res.x,res.y);}void sov(){    for(int i = 0 ; i < n ; i++){        int cnt = 0;        if(intersection(a[i],b[i],l11,l12) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],l11,l12);pii ans1=inter[cnt-1];flag1 = true;cout << "1: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],l21,l22) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],l21,l22);pii ans1=inter[cnt-1];flag2 = true;cout << "2: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],l31,l12) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],l31,l32);pii ans1=inter[cnt-1];flag3 = true;cout << "3: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],l41,l42) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],l41,l42);pii ans1=inter[cnt-1];flag4 = true;cout << "4: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],bl11,bl12) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],bl11,bl12);pii ans1=inter[cnt-1];flag5 = true;cout << "5: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],bl21,bl22) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],bl21,bl22);pii ans1=inter[cnt-1];flag6 = true;cout << "6: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],bl31,bl32) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],bl31,bl32);pii ans1=inter[cnt-1];flag7 = true;cout << "7: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}        if(intersection(a[i],b[i],bl41,bl42) ) {inter[cnt++] = GetLineIntersection(a[i],b[i],bl41,bl42);pii ans1=inter[cnt-1];flag8 = true;cout << "8: ( "<<ans1.first<<" , "<<ans1.second<<" )"<<endl;}    }}