poj1288poj1228Grandpa's Estate poj1113Wall

poj1288

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const double eps=1e-10;
const int N=1005;
inline int dcmp(int x){
    if(!x) return 0;
    return x>0?1:-1;
}
struct pt{
    int x,y;
    friend bool operator ==(pt a,pt b){
        return !dcmp(a.x-b.x)&&!dcmp(a.y-b.y);
    }
}p[N],ans[N];
int s[N],cnt;
inline int cross(pt a,pt b, pt c){
    return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
}
inline bool cmp(pt a,pt b){
    return (a.x<b.x)||(a.y<b.y && !dcmp(a.x-b.x));
}
void hull(int l,int r,pt a,pt b){
    int x=l,i=l-1,j=r+1,k;
    for(k=l;k<=r;k++){
        int tmp=dcmp(s[x]-s[k]);
        if(tmp<0||!tmp && cmp(p[x],p[k]))x=k;
    }
    pt y=p[x];
    for(k=l;k<=r;k++){
        s[++i]=cross(p[k],a,y);
        if(dcmp(s[i])>0)swap(p[i],p[k]);
        else i--;
    }
    for(k=r;k>=l;k--){
        s[--j]=cross(p[k],y,b);
        if(dcmp(s[j])>0)swap(p[j],p[k]);
        else j++;
    }
    if(l<=i)hull(l,i,a,y);
    ans[cnt++]=y;
    //cout<<y.x<<' '<<y.y<<endl;
    if(j<=r)hull(j,r,y,b);
}
int main(){
    int T,n,x;
    cin>>T;
    while(T--){
        memset(s,0,sizeof(s));
        cnt=x=0;
        cin>>n;
        for(int i=1;i<=n;i++){
            scanf("%d%d",&p[i].x,&p[i].y);
            if(!x || cmp(p[i],p[x]))x=i;
        }
        if(n<6){cout<<"NO"<<endl;continue;}
        swap(p[1],p[x]);
        ans[cnt++]=p[1];
        hull(2,n,p[1],p[1]);
        if(cnt<3){cout<<"NO"<<endl;continue;}
       //cout<<cnt<<endl;
        bool yes=true;
        for(int i=1;i<cnt&&yes;i++){
            yes=false;
            for(int j=2;j<=n&&!yes;j++){
                if(ans[i-1]==p[j] || ans[i]==p[j])continue;//sb的原来用标记函数判,wa了好几发
                if(!cross(ans[i],ans[i-1],p[j]))
                {yes=true;//printf(" %d %d %d\n ",i,p[j].x,p[j].y);
                }
            }
        }
        if(!yes){cout<<"NO"<<endl;continue;}
        yes=false;
        for(int j=2;j<=n&&!yes;j++){
                if(ans[0]==p[j] || ans[cnt-1]==p[j])continue;//
                if(!cross(ans[0],ans[cnt-1],p[j]))yes=true;
        }
        if(!yes)cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }
    return 0;
}

poj1113Wall

//˼·http://blog.youkuaiyun.com/zhengnanlee/article/details/9633357
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
const double eps =1e-10;
const double pi=acos(-1.0);
const int N=1005;
inline int dcmp(int x){
    if(!x) return 0;
    return x>0?1:-1;
}
struct pt{
    int x,y;
}ans[N],temp,p[N];
int s[N],cnt;
double sum=0;
inline bool cmp(pt a,pt b){
    return (a.x<b.x) || (a.y<b.y)&& !dcmp(a.x-b.x);
}
inline int cross(pt a,pt b,pt c){
    return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
}
inline double dis(pt a,pt b){
    return sqrt((double)(a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
void hull(int l,int r,pt a,pt b){
    int x=l,i=l-1,j=r+1,k;
    for(k=l; k<=r; k++){
        int tmp=dcmp(s[x]-s[k]);
        if(tmp<0 || !tmp && cmp(p[x],p[k]))x=k;
    }
    pt y=p[x];
    for(k=l;k<=r;k++){
        s[++i]=cross(p[k],a,y);
        if(dcmp(s[i])>0) swap(p[i],p[k]);
        else i--;
    }
    for(k=r;k>=l;k--){
        s[--j]=cross(p[k],y,b);
        if(dcmp(s[j])>0)swap(p[j],p[k]);
        else j++;
    }
    if(l<=i)hull(l,i,a,y);
    //cout<<y.x<<' '<<y.y<<endl;
    sum+=dis(temp,y);
    temp=y;
    //cout<<sum<<'a'<<endl;
    if(j<=r)hull(j,r,y,b);
}
int main(){
    int n,l,x=0;
    cin>>n>>l;
    for(int i=1; i<=n ;i++){
        scanf("%d%d",&p[i].x,&p[i].y);
        if(!x || cmp(p[i],p[x]))x=i;
    }
    swap(p[1],p[x]);
    temp=p[1];
    hull(2,n,p[1],p[1]);
    cout<<(int)(sum+0.5+2*pi*l+dis(temp,p[1]))<<endl;
    return 0;
}