Cod sursa(job #1894007)

Utilizator CiurezAndreiCiurez Marius-Andrei CiurezAndrei Data 26 februarie 2017 13:02:43
Problema Cele mai apropiate puncte din plan Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 2.07 kb
#include <bits/stdc++.h>

#define INF 20000000000000000

using namespace std;

ifstream fin("cmap.in");
ofstream fout("cmap.out");

int N;
pair<long long, long long> X[100010], Y[100010], v[100010];

inline long long dist(const pair<long long, long long> &a, const pair<long long, long long> &b)
{
    return  (a.first - b.first) * (a.first - b.first) + (a.second - b.second) * (a.second - b.second) ;
}

inline void interclasare(const int &left, const int &middle, const int &right)
{
    int i = left, k = 0;
    int j = middle + 1;

    while(i <= middle && j <= right)
    {
        (X[i].first <= X[j].first) ? (Y[++ k] = X[i ++]) : (Y[++ k] = X[j ++]);
    }
    while(i <= middle)
    {
        Y[++ k] = X[i ++];
    }
    while(j <= right)
    {
        Y[++ k] = X[j ++];
    }
    for(int i = left; i <= right; i ++)
    {
        X[i] = Y[i - left + 1];
    }
}

inline long long closestPoints(int left, int right, pair<long long, long long> X[100010])
{
    if(left >= right - 1) // sunt mai putin de 3 puncte
        return INF;

    if(right - left == 2)
    {
        if(X[left] > X[left + 1])
            swap(X[left], X[left + 1]);

        return dist(X[left], X[left + 1]);
    }

    int middle = (left + right) >> 1;
    long long solution = min( closestPoints(left, middle, X), closestPoints(middle, right, X) );

    interclasare(left, middle, right);

    int k = 0;
    for(int i = left; i < right; i ++)
    {
        if( abs(X[i].first - X[middle].first) <= solution) // diferenta x-lor mai mica ca solution
        {
            v[++k] = X[i];
        }
    }

    for(int i = 1; i < k; i ++)
    {
        for(int j = i + 1; j <= k && j - i < 8; j ++)
        {
            solution = min(solution, dist(v[i], v[j]));
        }
    }

    return solution;

}

int main()
{
    fin >> N;

    for(int i = 1; i <= N; i ++)
    {
        fin >> X[i].first >> X[i].second;
    }

    sort(X + 1, X + N + 1);

    fout << setprecision(6) << fixed << sqrt( closestPoints(0, N, X) );

    return 0;
}