uva 10902 Pick-up Sticks

题意：有n根木条，一根一根的往一个坐标系上丢(给出木条两点的坐标)，问最后不被覆盖的木条有哪些，即丢的木条如果和前面丢的木条交叉的话，就会覆盖前面那根木条。

博主呢一开始直接在uva11343上改了输入，然后提交了，结果TLE。。。看了下题中范围，比较大，所以改用输一个删一堆

/*线段相交*/#include <iostream>#include <cstdio>#include <cstdlib>#include <vector>//#define T#define def 1e-6using namespace std;//点struct Point{    double x;    double y;};//线struct Line{    Point p1;    Point p2;    int flag;};//判断点在pi-pj在线段的那一侧int direction(Point* pi,Point* pj,Point* pk){    Point p1,p2;    p1.x = pk->x - pi->x;    p1.y = pk->y - pi->y;    p2.x = pj->x - pi->x;    p2.y = pj->y - pi->y;    double cross = p1.x*p2.y - p2.x*p1.y;    if(cross >= def)        return 1;    else if(cross <= -def)        return -1;    else        return 0;}//判断点是否在pi和pj为对角点的矩形里bool onSegment(Point* pi,Point* pj,Point* pk){    double minx,miny,maxx,maxy;    if(pi->x > pj->x)    {        minx = pj->x;        maxx = pi->x;    }    else    {        minx = pi->x;        maxx = pj->x;    }    if(pi->y > pj->y)    {        miny = pj->y;        maxy = pi->y;    }    else    {        miny = pi->y;        maxy = pj->y;    }    return (minx <= pk->x)&&(maxx >= pk->x)&&(miny <=pk->y)&&(maxy >= pk->y);}//判断线段相交bool segmentIntersect(Point* p1,Point* p2,Point* p3,Point* p4){    int d1 = direction(p3,p4,p1);    int d2 = direction(p3,p4,p2);    int d3 = direction(p1,p2,p3);    int d4 = direction(p1,p2,p4);    if(d1*d2 < 0&&d3*d4 < 0)        return true;    if(!d1 && onSegment(p3,p4,p1))        return true;    if(!d2 && onSegment(p3,p4,p2))        return true;    if(!d3 && onSegment(p1,p2,p3))        return true;    if(!d4 && onSegment(p1,p2,p4))        return true;    return false;}vector<Line> LL;vector<Line>::iterator it;int main(){    //Point p1,p2,p3,p4;#ifdef T    freopen("in.txt","r",stdin);    freopen("out.txt","w",stdout);#endif // T    int n,i,t;    double a,b,c,d;    Line L;    while(scanf("%d",&n)&&n)    {        t=0;        LL.clear();        for(i=1;i<=n;i++)        {            scanf("%lf %lf %lf %lf",&a,&b,&c,&d);            L.p1.x = a;L.p1.y = b;            L.p2.x = c;L.p2.y = d;            L.flag = i;            for(it = LL.begin();it != LL.end();)            {                if(segmentIntersect(&L.p1,&L.p2,&it->p1,&it->p2))                {                    LL.erase(it);                }                else                    it++;            }           LL.push_back(L);        }        printf("Top sticks:");        for(it = LL.begin();it != LL.end();it++)        {                    if(t) printf(",");                    printf(" %d",it->flag); t=1;        }        printf(".\n");    }   return 0;}