Submission #129554

#	Time	Username	Problem	Language	Result	Execution time	Memory
129554		johutha	Towns (IOI15_towns)	C++14	13 / 100	23 ms	504 KiB

towns

#include "towns.h"
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

bool samecomp(vector<int> &lngv, int v1, int v2, int r)
{
	if (lngv[v1] + lngv[2] - 2*r > getDistance(v1, v2)) return true;
	return false;
}

int hubDistance(int n, int sub) {
	int mmax = -1;
	int diabeg = -1;
	for (int i = 1; i < n; i++)
	{
		int q = getDistance(0, i);
		if (q > mmax)
		{
			mmax = q;
			diabeg = i;
		}
	}
	vector<int> fbeg(n);
	int diaend = -1;
	mmax = -1;
	for (int i = 0; i < n; i++)
	{
		if (i == diabeg) continue;
		fbeg[i] = getDistance(diabeg, i);
		if (fbeg[i] > mmax)
		{
			mmax = fbeg[i];
			diaend = i;
		}
	}
	vector<int> fend(n);
	fend[diabeg] = fbeg[diaend];
	for (int i = 0; i < n; i++)
	{
		if (i == diabeg || i == diaend) continue;
		fend[i] = getDistance(diaend, i);
	}

	int r = 100000000;
	int dia = fbeg[diaend];

	for (int i = 0; i < n; i++)
	{
		int diff = abs(fbeg[i] - fend[i]);
		r = min(r, (dia + diff)/2);
	}

	for (int i = 0; i < n; i++)
	{
		if (r == (dia + abs(fbeg[i] - fend[i]))/2)
		{
			if (fbeg[i] - fend[i] < 0)
			{
				swap(fbeg, fend);
				swap(diabeg, diaend);
			}
			break;
		}
	}

	vector<int> ext;
	int cntl = 0, cntr = 0;
	for (int i = 0; i < n; i++)
	{
		if (r == (dia + fbeg[i] - fend[i])/2)
		{
			ext.push_back(i);
		}
		else
		{
			if ((dia + fbeg[i] - fend[i])/2 < r) cntl++;
			else cntr++;
		}
		
	}

	if (cntl > (n / 2) || cntr > (n/2)) return -r;

	vector<int> st;

	for (int j : ext)
	{
		if (st.empty())
		{
			st.push_back(j);
		}
		else
		{
			if (samecomp(fbeg, j, st.back(), r)) st.push_back(j);
			else st.pop_back();
		}
	}

	if (st.empty()) return r;
	int cnt = 0;
	for (int i : ext)
	{
		if (i == st.back()) continue;
		else cnt += (samecomp(fbeg, i, st.back(), r));
	}

	return r;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:14:28: warning: unused parameter 'sub' [-Wunused-parameter]
 int hubDistance(int n, int sub) {
                            ^~~

• Subtask 1: 13 / 13
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39