mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
163 lines
3.3 KiB
C++
163 lines
3.3 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<math.h>
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#include<algorithm>
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using namespace std;
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const int M=50005;
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typedef struct Point
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{
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double x;
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double y;
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}Point;
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Point p[M];
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Point pp[M];
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bool bo[M];
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int stack[M];
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double dis(Point A,Point B)
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{
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return sqrt((B.x-A.x)*(B.x-A.x)+(B.y-A.y)*(B.y-A.y));
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}
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bool cmp(Point a,Point b)
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{
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if(a.x<b.x)
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return true;
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if(a.x>b.x)
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return false;
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if(a.y<b.y)
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return true;
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return false;
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}
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double Xdet(Point A,Point B,Point C)
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{
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double x1,x2,y1,y2;
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x1=B.x-A.x;
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y1=B.y-A.y;
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x2=C.x-A.x;
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y2=C.y-A.y;
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return x1*y2-x2*y1;
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}
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void Gram_Scan(Point *p,int &n)
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{
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int i,t;
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sort(p+1,p+1+n,cmp);
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for(t=0,i=1;i<=n;i++)
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{
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if(i>1&&p[i].x==p[i-1].x&&p[i].y==p[i-1].y)
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continue;
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p[++t]=p[i];
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}
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n=t;
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t=0;
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memset(bo+1,true,n*sizeof(bo[0]));
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if(n>0)
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{
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stack[++t]=1;
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bo[stack[t]]=false;
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}
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if(n>1)
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{
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stack[++t]=2;
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bo[stack[t]]=false;
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}
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if(n>2)
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{
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for(i=3;i<n;i++)
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if(bo[i]&&Xdet(p[stack[t-1]],p[stack[t]],p[i])>=0)
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{
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stack[++t]=i;
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bo[i]=false;
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}
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else
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{
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while(t>=2&&Xdet(p[stack[t-1]],p[stack[t]],p[i])<0)
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{
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bo[stack[t]]=true;
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t--;
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}
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stack[++t]=i;
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bo[stack[t]]=false;
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}
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for(i=n;i>=1;i--)
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if(bo[i]&&Xdet(p[stack[t-1]],p[stack[t]],p[i])>=0)
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{
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stack[++t]=i;
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bo[i]=false;
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}
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else
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{
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while(t>=2&&Xdet(p[stack[t-1]],p[stack[t]],p[i])<0)
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{
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bo[stack[t]]=true;
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t--;
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}
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stack[++t]=i;
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bo[stack[t]]=false;
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}
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t--;
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}
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for(i=1;i<=t;i++)
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pp[i]=p[stack[i]];
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memcpy(p+1,pp+1,t*sizeof(Point));
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n=t;
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}
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int n,o[M],on;
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int dcmp(double a,double b)
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{
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if(a-b<1e-10&&b-a<1e-10)
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return 0;
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if(a>b)
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return 1;
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return -1;
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}
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bool cmp1(const Point &a,Point &b)
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{
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return dcmp(a.x,b.x)<0;
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}
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bool cmp2(const int&a,const int&b)
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{
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return dcmp(p[a].y,p[b].y)<0;
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}
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double min(double a,double b)
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{
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return a<b?a:b;
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}
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double search(int s,int t)
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{
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int mid=(s+t)/2,i,j;
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double ret=1e300;
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if(s>=t)
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return ret;
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for(i=mid;i>=s&&!dcmp(p[i].x,p[mid].x);i--);ret=search(s,i);
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for(i=mid;i<=t&&!dcmp(p[i].x,p[mid].x);i++);ret=min(ret,search(i,t));on=0;
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for(i=mid;i>=s&&dcmp(p[mid].x-p[i].x,ret)<=0;i--)o[++on]=i;
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for(i=mid+1;i<=t&&dcmp(p[i].x-p[mid].x,ret)<=0;i++)o[++on]=i;
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sort(o+1,o+on+1,cmp2);
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for(i=1;i<=on;i++)
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for(j=1;j<=10;j++)
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if(i+j<=on)
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ret=min(ret,dis(p[o[i]],p[o[i+j]]));
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return ret;
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}
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int main()
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{
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int n,i,count=0,j;
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double shortdis,longdis;
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while(scanf("%d",&n),n)
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{
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for(i=1;i<=n;i++)
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scanf("%lf%lf",&p[i].x,&p[i].y);
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sort(p+1,p+n+1,cmp1);
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shortdis=search(1,n);
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longdis=0;
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Gram_Scan(p,n);
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for(i=1;i<=n-1;i++)
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for(j=i+1;j<=n;j++)
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if(dis(p[i],p[j])>longdis)
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longdis=dis(p[i],p[j]);
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printf("Case %d:\n",++count);
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printf("Distance of the nearest couple is %.3lf\n",shortdis);
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printf("Distance of the most distant couple is %.3lf\n\n",longdis);
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}
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return 0;
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}
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