Cod sursa(job #2864546)

Utilizator roberttrutaTruta Robert roberttruta Data 7 martie 2022 22:41:04
Problema Cele mai apropiate puncte din plan Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.68 kb
#include <fstream>
#include <algorithm>
#include <cmath>
#include <iomanip>

using namespace std;
ifstream f("cmap.in");
ofstream g("cmap.out");

struct point
{
    int x,y;
}v[100005];
int u[100005];

bool by_x(point a, point b)
{
    if(a.x == b.x)
        return a.y < b.y;
    return a.x < b.x;
}
bool by_y(int a, int b)
{
    if(v[a].y == v[b].y)
        return v[a].x < v[b].x;
    return v[a].y < v[b].y;
}

double dis(int a, int b)
{
    long long x1 = v[a].x;
    long long x2 = v[b].x;
    long long y1 = v[a].y;
    long long y2 = v[b].y;
    long long x = (x1 - x2)*(x1 - x2);
    long long y = (y1 - y2)*(y1 - y2);
    return sqrt(x + y);
}

double combine(int s, int d, double width)
{
    double Min=width;
    int nr = 0, mij = (s+d)/2;
    for(int i=s; i<=d; i++)
        if(abs(v[i].x - v[mij].x) < width)
            u[nr++] = i;

    sort(u, u+nr, by_y);
    for(int i=0; i<nr; i++)
        for(int j=i+1; j<nr && j<=i+7; j++)
            Min = min(Min, dis(u[i], u[j]));
    return Min;
}

double divide_et_impera(int s, int d)
{
    double Min;
    if(d-s <= 2)
    {
        Min = dis(s, s+1);
        if(d-s == 2)
        {
            Min = min(Min, dis(s, s+2));
            Min = min(Min, dis(s+1, s+2));
        }
        return Min;
    }
    int mij = (s+d)/2;
    Min = min(divide_et_impera(s, mij), divide_et_impera(mij+1, d));
    Min = min(Min, combine(s, d, Min));
    return Min;
}

int main()
{
    int n,i;
    f>>n;
    for(i=1; i<=n; i++)
    {
        f>>v[i].x;
        f>>v[i].y;
    }
    sort(v+1, v+1+n, by_x);

    g<<setprecision(6)<<fixed<<divide_et_impera(1, n);

    return 0;
}