poj 3304——Segments

幾何入門

先貼著http://blog.csdn.net/wangjian8006

#include<iostream>#include<cstdio>#include<algorithm>#include<cmath>using namespace std;#define eps 1e-8#define maxn 110struct Line{double x1,y1,x2,y2;void input(double a,double b,double c,double d){x1=a,y1=b,x2=c,y2=d;}}L[maxn];int n;int sgn(double x){return x<-eps?-1:x>eps?1:0;}double dis(double x1,double y1,double x2,double y2){return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}double cross(double x1,double y1, double x2,double y2,double x,double y){return (x2-x1)*(y-y1)-(x-x1)*(y2-y1);}bool judge(double x1,double y1,double x2,double y2){if(dis(x1,y1,x2,y2)<eps) return 0;for(int i=0;i<n;i++)if(cross(x1,y1,x2,y2,L[i].x1,L[i].y1)*cross(x1,y1,x2,y2,L[i].x2,L[i].y2)>eps) return 0;return 1;}int main(){int t;double a,b,c,d;scanf("%d",&t);while(t--){scanf("%d",&n);for(int i=0;i<n;i++){scanf("%lf%lf%lf%lf",&a,&b,&c,&d);L[i].input(a,b,c,d);}if(n==1){printf("Yes!\n");continue;}int ans=0;for(int i=0;i<n&&!ans;i++)for(int j=i+1;j<n&&!ans;j++)if( judge(L[i].x1,L[i].y1,L[j].x1,L[j].y1) ||judge(L[i].x1,L[i].y1,L[j].x2,L[j].y2) ||judge(L[i].x2,L[i].y2,L[j].x1,L[j].y1) ||judge(L[i].x2,L[i].y2,L[j].x2,L[j].y2))ans=1;if(ans)printf("Yes!\n");elseprintf("No!\n");}return 0;}