poj1288poj1228Grandpa's Estate poj1113Wall

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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.csdn.net/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;}

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