Cod sursa(job #1779413)

Utilizator andreiudilaUdila Andrei andreiudila Data 15 octombrie 2016 12:03:04
Problema Cele mai apropiate puncte din plan Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.36 kb
#include <fstream>
#include <math.h>
#include <algorithm>
#include <iomanip>
using namespace std;
ifstream cin("cmap.in");
ofstream cout("cmap.out");

int n,i;


int x1,y1;
struct punct{
int x,y;
}a[100001],aux[100001];

bool cmp(punct a, punct b)
{
    return a.x<b.x;
}
bool cmp2(punct a, punct b)
{
    return a.y<b.y;
}

double dist(punct a, punct b)
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

double solutie(int l, int r)
{
    double mini=1000000000;

    if(l-r<3)
    {
        for(int i=l;i<=r;++i)
            for(int j=i+1;j<=r;++j)
        {
            double d=dist(a[i],a[j]);
            if(d<mini) mini=d;
        }

        return mini;
    }

    double st=solutie(l,(l+r)/2);
    double dr=solutie((l+r)/2+1, r);

    double mid=(a[(l+r)/2].x+a[(l+r)/2+1].x)/2;

    int nr=0;

    for(int i=l;i<=r;++i)
    {
        if(fabs(a[i].x-mid)<min(st,dr)) aux[++nr]=a[i];
    }

    sort(aux+1,aux+nr+1,cmp2);

    double sol=min(st,dr);

    for(int i=l;i<=r-6;++i)
        for(int j=i+1;j<=i+7;++j)
            sol=min(sol,dist(aux[i],aux[j]));


    return sol;
}
int main()
{
    cin>>n;
    for(i=1;i<=n;++i)
    {
        cin>>x1>>y1;
        a[i].x=x1;
        a[i].y=y1;
    }

    sort(a+1,a+n+1,cmp);

    cout<<setprecision(6)<<fixed<<solutie(1,n);

    return 0;
}