poj2653 线段相交+滚动数组更新结果

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<string>
#include<stdlib.h>
#include<cmath>
#include<queue>
#include<algorithm>
using namespace std;
#define rd(x) scanf("%d",&x)
#define rdd(x,y) scanf("%d%d",&x,&y)
#define rddd(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define rds(s) scanf("%s",s)
#define rep(i,n) for(int i=0;i<n;i++)
#define LL long long
const int N = 100;
const int M=5e5+10;
const int inf=1e9;
const double eps=1e-5;
const int MOD=1e9+7;
int n,m;
struct Point{
double x,y;
Point(){

}
Point(double _x,double _y){
x=_x;y=_y;
}
};
Point p1,p2,p3,p4;
struct Seg{
Point s,e;
Seg(){}
Seg(Point _s,Point _e){
s=_s;
e=_e;
}
Seg(double x,double y,double xx,double yy){
s.x=x;s.y=y;
e.x=xx;e.y=yy;
}
};
double cross(Point a,Point b,Point c){
return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
}
double dist(Point a,Point b){
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
int sgn(double x){ return x<-eps?-1:x<eps?0:1;}

bool jiao(Seg a,Seg b){
Point p1,p2,p3,p4;
p1=a.s;p2=a.e;
p3=b.s;p4=b.e;
if(min(p1.x,p2.x)<=max(p3.x,p4.x) &&
min(p3.x,p4.x)<=max(p1.x,p2.x) &&
min(p1.y,p2.y)<=max(p3.y,p4.y) &&
min(p3.y,p4.y)<=max(p1.y,p2.y) &&
sgn(cross(p1,p2,p3))*sgn(cross(p1,p2,p4))<=0 &&
sgn(cross(p3,p4,p1))*sgn(cross(p3,p4,p2))<=0 ) return true;
return false;
}
Seg seg[100005];
int dp[2][100005];
int main()
{
#ifndef ONLINE_JUDGE
freopen("aaa","r",stdin);
#endif
int T;
while(true){
rd(n);
if(n==0) break;
for(int i=1;i<=n;i++){
double u,v,w,z;
scanf("%lf%lf%lf%lf",&u,&v,&w,&z);
seg[i]=Seg(u,v,w,z);
}
int c=0;
int cnt=0;
for(int i=1;i<=n;i++){
int nxt=c^1;
int cnt2=0;
for(int j=0;j<cnt;j++){
if(jiao(seg[dp[c][j]],seg[i])) continue;
dp[nxt][cnt2++]=dp[c][j];
}
dp[nxt][cnt2++]=i;
c^=1;cnt=cnt2;
}
printf("Top sticks: ");
for(int i=0;i<cnt;i++){
printf("%d%s",dp[c][i],i==cnt-1?".\n":", ");
}
}

return 0;
}