Cod sursa(job #1035838)

Utilizator thewildnathNathan Wildenberg thewildnath Data 18 noiembrie 2013 20:27:41
Problema Cele mai apropiate puncte din plan Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.62 kb
#include<stdio.h>
#include<algorithm>
#include<math.h>
using namespace std;

#define INF 2000000000
#define NMAX 100003

struct punct
{
    int x,y;
};
int n,na,poz[NMAX];
punct v[NMAX],a[NMAX];


inline bool cmpx(const punct &a,const punct &b)
{return a.x<b.x;}

inline bool cmpy(const punct &a,const punct &b)
{return a.y<b.y;}


inline double dist(punct i,punct j)
{
    return sqrt((i.x-j.x)*(i.x-j.x) + (i.y-j.y)*(i.y-j.y));
}


inline double caz3(int l,int r)
{
    double sol=INF;
    if(r-l+1>=2)
        sol=dist(v[poz[l]],v[poz[l+1]]);
    if(r-l+1==3)
    {
        sol=min(sol,dist(v[poz[l]],v[poz[l+2]]));
        sol=min(sol,dist(v[poz[l+1]],v[poz[l+2]]));
    }

    return sol;
}


double rez(int l,int r)
{
    double sol=INF;
    if(r-l+1<=3)
    {
        sol=caz3(l,r);
        return sol;
    }
    int med=(l+r)>>1,i,j,p=1;

    sol=min(rez(l,med) , rez(med+1,r));
    na=0;
    for(i=l;i<=r;++i)
        if(abs(v[poz[med]].x-v[poz[i]].x)<=sol)
            a[++na]=v[poz[i]];

    sort(a+1,a+1+na,cmpy);                       //

    for(i=2;i<=na;++i)
    {
        while(a[i].y-a[p].y>sol)
            ++p;
        for(j=p;j<i;++j)
            sol=min(sol,dist(a[i],a[j]));
    }

    return sol;
}


int main()
{
    freopen("cmap.in","r",stdin);
    freopen("cmap.out","w",stdout);
    int i;
    double sol;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
    {
        scanf("%d%d",&v[i].x,&v[i].y);
        poz[i]=i;
    }
    sort(v+1,v+1+n,cmpx);                       //

    sol=rez(1,n);

    printf("%.6lf\n",sol);

    return 0;
}