[hdu-4946] Area of Mushroom 计算几何 凸包

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
#include<stack>
#include<time.h>
#include<cstdlib>
#include<cmath>
#include<list>
using namespace std;
#define MAXN 100100
#define eps 1e-9
#define For(i,a,b) for(int i=a;i<=b;i++) 
#define Fore(i,a,b) for(int i=a;i>=b;i--) 
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define mkp make_pair
#define pb push_back
#define cr clear()
#define sz size()
#define met(a,b) memset(a,b,sizeof(a))
#define iossy ios::sync_with_stdio(false)
#define fre freopen
#define pi acos(-1.0)
#define inf 1e6+7
#define Vector Point
const int Mod=1e9+7;
typedef unsigned long long ull;
typedef long long ll;
int dcmp(double x){
    if(fabs(x)<=eps) return 0;
    return x<0?-1:1;
}
struct Point{
    double x,y;
    int v;
    int id;
    Point(double x=0,double y=0):x(x),y(y) {}
    bool operator < (const Point &a)const{
        if(x==a.x && y==a.y) return v<a.v;
        if(x==a.x) return y<a.y;
        return x<a.x;
    }
    Point operator - (const Point &a)const{
        return Point(x-a.x,y-a.y);
    }
    Point operator + (const Point &a)const{
        return Point(x+a.x,y+a.y);
    }
    Point operator * (const double &a)const{
        return Point(x*a,y*a);
    }
    Point operator / (const double &a)const{
        return Point(x/a,y/a);
    }
    void read(){
        scanf("%lf%lf",&x,&y);
        scanf("%d",&v);
    }
    void out(){
        cout<<"debug: "<<x<<" "<<y<<endl;
    }
    bool operator == (const Point &a)const{
        return dcmp(x-a.x)==0 && dcmp(y-a.y)==0;
    }
    bool operator !=(const Point &a)const{
        return dcmp(x-a.x)!=0 || dcmp(y-a.y)!=0;
    }
};
double Dot(Vector a,Vector b) {
    return a.x*b.x+a.y*b.y;
}
double dis(Vector a) {
    return Dot(a,a);
}
double Cross(Point a,Point b){
    return a.x*b.y-a.y*b.x;
}
bool cmp(Point a,Point b){
    if(a.x==b.x) return a.y<b.y;
    return a.x<b.x;
}
int vt[5005];
int ConvexHull(Point *p,int n,Point *ch,int maxv){
    sort(p,p+n,cmp);
    int m=0;
    for(int i=0;i<n;i++){
        while(m>1 && Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
        ch[m++]=p[i];
    }
    int k=m;
    for(int i=n-2;i>=0;i--){
        while(m>k && Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
        ch[m++]=p[i];
    }
    if(n>1) m--;
    return m;
}
int n;
Point p[5005];
Point ch[5005];
Point pp[5005];
char s[5005];
void solve(){
    met(vt,0);
    int maxv=0;
    s[n]=‘\0‘;
    int rt=0;
    For(i,0,n-1) s[i]=‘0‘;
    For(i,0,n-1) p[i].read(),p[i].id=i;
    sort(p,p+n);
    For(i,1,n-1) {
        if(p[i]==p[i-1] && p[i].v==p[i-1].v) vt[p[i].id]=1,vt[p[i-1].id]=1;
    }
    For(i,0,n-1) maxv=max(maxv,p[i].v);
    For(i,0,n-1)  if(p[i].v==maxv) pp[rt++]=p[i];
    if(maxv==0){
        puts(s);
        return ;
    }
    int m=ConvexHull(pp,rt,ch,maxv);    
    For(i,0,m-1){
        if(!vt[ch[i].id]) s[ch[i].id]=‘1‘;
    }
    For(i,0,rt-1) {
//            cout<<"Bug: "<<pp[i].id<<" "<<vt[pp[i].id]<<endl;
//            pp[i].out();
        For(j,0,m-1){
            if(dcmp(Cross(ch[j]-pp[i],ch[(j+1)%m]-pp[i]))==0 && !vt[pp[i].id]) {s[pp[i].id]=‘1‘;break;}
        }
    }
    puts(s);
}
int main(){
//    fre("in.txt","r",stdin);
    int t=0;
    while(~scanf("%d",&n) && n)    printf("Case #%d: ",++t),solve();
    return 0;
}