Submission #119437

#	Time	Username	Problem	Language	Result	Execution time	Memory
119437		davitmarg	Triangles (CEOI18_tri)	C++17	0 / 100	2 ms	384 KiB

tri

/*DavitMarg*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <stack>
#include <cassert>
#include <iterator>
#include <bitset>
#include <fstream>

#ifndef death
#include<trilib.h>
#endif // death

#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin(),v.end()
using namespace std;

#ifdef death

int get_n()
{
	cout << "N::" << endl;
	int x;
	cin >> x;
	return x;
}

bool is_clockwise(int a, int b, int c)
{
	cout << ":::" << a << " " << b << " " << c << endl;
	int x;
	cin >> x;
	return x;
}

void give_answer(int x)
{
	cout << x << endl;
}

#endif // death

map<pair<int, pair<int, int>>, bool> used, pre;

bool cw(int a, int b, int c)
{

	if (a == b || b == c || c == a)
		return 1;
	if (used[MP(a, MP(b, c))])
		return pre[MP(a, MP(b, c))];
	used[MP(a, MP(b, c))] = 1;
	return pre[MP(a, MP(b, c))] = is_clockwise(a, b, c);
}

bool ccw(int a, int b, int c)
{
	if (a == b || b == c || c == a)
		return 1;
	return !cw(a, b, c);
}

int convex(vector<int> p)
{
	vector<int> up, down;
	vector<bool> uUp(p.size() + 5), uDown(p.size() + 5);
	int st, en;

	st = p[0];
	en = p.back();

	reverse(all(p));
	p.pop_back();
	reverse(all(p));
	p.pop_back();

	vector<int> add = p;
	p.clear();
	p.PB(st);
	for (int i = 0; i < add.size(); i++)
		for (int j = 0; j < add.size(); j++)
			p.PB(add[j]);
	p.PB(en);

	up.PB(p[0]);
	down.PB(p[0]);
	for (int i = 1; i < p.size(); i++)
	{
		if (i == p.size() - 1 || (!uUp[p[i]] && cw(p[0], p[i], p[p.size() - 1])))
		{
			while (up.size() > 1 && (!cw(up[up.size() - 2], up[up.size() - 1], p[i]) || up.back() == p[i]))
			{
				uUp[up.back()] = 0;
				up.pop_back();
			}
			up.PB(p[i]);
			uUp[up.back()] = 1;
		}

		if (i == p.size() - 1 || (!uDown[p[i]] && ccw(p[0], p[i], p[p.size() - 1])))
		{
			while (down.size() > 1 && (!ccw(down[down.size() - 2], down[down.size() - 1], p[i]) || down.back() == p[i]))
			{
				uDown[down.back()] = 0;
				down.pop_back();
			}
			down.PB(p[i]);
			uDown[down.back()] = 1;
		}
	}
	down.pop_back();
	reverse(all(down));
	down.pop_back();
	reverse(all(down));
	while (!down.empty())
	{
		up.PB(down.back());
		down.pop_back();
	}

	for (int i = 0; i < up.size(); i++)
		if (!cw(up[i], up[(i + 1) % up.size()], up[(i + 2) % up.size()]))
			return 0;

	return up.size();
}

int ans, n;
vector<int> p;
int main()
{
	n = get_n();
	for (int i = 1; i <= n; i++)
		p.PB(i);
	for (int i = 0; i < n; i++)
		for (int j = 0; j < n; j++)
		{
			if (i == j)
				continue;
			swap(p[0], p[i]);
			swap(p.back(), p[j]);
			ans = max(ans, convex(p));
			swap(p[0], p[i]);
			swap(p.back(), p[j]);
		}
	give_answer(ans);
	return 0;
}


/*

4
1
0
0
0
1
1


*/

Compilation message (stderr)

tri.cpp: In function 'int convex(std::vector<int>)':
tri.cpp:92:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < add.size(); i++)
                  ~~^~~~~~~~~~~~
tri.cpp:93:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < add.size(); j++)
                   ~~^~~~~~~~~~~~
tri.cpp:99:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 1; i < p.size(); i++)
                  ~~^~~~~~~~~~
tri.cpp:101:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (i == p.size() - 1 || (!uUp[p[i]] && cw(p[0], p[i], p[p.size() - 1])))
       ~~^~~~~~~~~~~~~~~
tri.cpp:112:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (i == p.size() - 1 || (!uDown[p[i]] && ccw(p[0], p[i], p[p.size() - 1])))
       ~~^~~~~~~~~~~~~~~
tri.cpp:133:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < up.size(); i++)
                  ~~^~~~~~~~~~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 25