#include<stdio.h>
#include<string.h>
#include<math.h>
#define mini 0.00000001
typedef struct
{
	double x,y;
}point;
struct
{
	point p[2]; 
}line[10000];
double max(double a,double b);
double min(double a,double b);
int onsegment(point p,point p1,point p2);
int direction(point p1,point p0,point p2);
int segmentsintersection(point p1,point p2,point p3,point p4);
double distance(double x1,double y1,double x2,double y2);
int main()
{
	int test,n,i,j,k,t,q,flag;
	double px1,px2,py1,py2;
	point p1,p2;
	scanf("%d",&test);
	while(test--)
	{
		scanf("%d",&n);	
		for(i=0;i<n;i++)scanf("%lf%lf%lf%lf",&line[i].p[0].x,&line[i].p[0].y,&line[i].p[1].x,&line[i].p[1].y);
		if(n==1||n==2)printf("Yes!\n");
		else
		{
			for(i=0;i<n;i++)
			{
				for(j=i;j<n;j++)
				{
					for(k=0;k<=1;k++)
					{
						for(t=0;t<=1;t++)
						{
							px1=line[i].p[k].x;py1=line[i].p[k].y;
							px2=line[j].p[t].x;py2=line[j].p[t].y;
							if(distance(px1,py1,px2,py2)>=mini)
							{
								flag=1;
								p1.x=px1;p1.y=py1;
								p2.x=px2;p2.y=py2;
								for(q=0;q<n;q++)
								{
									if(!segmentsintersection(p1,p2,line[q].p[0],line[q].p[1]))
									{
										flag=0;
										break;
									}
								}
								if(flag)
								{
									goto omllyf;
								}
							}
						}
					}
				}
			}
			omllyf:	if(flag)printf("Yes!\n");
			else printf("No!\n");
		}
	}
	return 0;
}
int direction(point p1,point p0,point p2)
{
	double temp=(p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y);
	if(temp>mini)return 1;
	if(temp<-mini)return -1;
	return 0;
}
int segmentsintersection(point p1,point p2,point p3,point p4)
{
	int d1,d2,d3,d4;
	d1=direction(p3,p4,p1);
	d2=direction(p3,p4,p2);
	d3=direction(p1,p2,p3);
	d4=direction(p1,p2,p4);
	if(d1*d2<0&&d3*d4<0)return 1;
	if(!d1&&onsegment(p1,p3,p4))return 1;
	if(!d2&&onsegment(p2,p3,p4))return 1;
	if(!d3&&onsegment(p3,p1,p2))return 1;
	if(!d4&&onsegment(p4,p1,p2))return 1;
	return 0;
}
int onsegment(point p,point p1,point p2)
{
	if(p.x>=min(p1.x,p2.x)&&p.x<=max(p1.x,p2.x)&&p.y>=min(p1.y,p2.y)&&p.y<=max(p1.y,p2.y))return 1;
	return 0;
}
double max(double a,double b){if(a>b)return a;return b;}
double min(double a,double b){if(a<b)return a;return b;}
double distance(double x1,double y1,double x2,double y2)
{
	double temp;
	temp=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
	return temp;
}

• Re:找到我的程序WA的原因你就AC了!用C写的 (15) linweihong 2012-12-27 20:54:26