Submission #267159

#	Time	Username	Problem	Language	Result	Execution time	Memory
267159		Kenzo_1114	Triangles (CEOI18_tri)	C++17	0 / 100	1 ms	384 KiB

tri

#include<bits/stdc++.h>
#include"trilib.h"
using namespace std;
const int MAXN = 40010;

/*
int get_n()
{
	int aux;
	scanf("%d", &aux);
	return aux;
}

bool is_clockwise(int a, int b, int c)
{
	char aux;
	printf("? %d %d %d\n", a, b, c);
	scanf(" %c", &aux);
	return (aux == 'y');
}

void give_answer(int s)
{
	printf("%d\n", s);
}
*/


set<pair<int, int> > ch;
set<pair<int, int> > :: iterator it;
bool marc[MAXN], ans[MAXN];
int adj[MAXN];

int main ()
{
	int n = get_n();

	if(!is_clockwise(1, 2, 3))	ch.insert({2, 1}), ch.insert({3, 2}), ch.insert({1, 3});
	else						ch.insert({1, 2}), ch.insert({2, 3}), ch.insert({3, 1});
	marc[1] = marc[2] = marc[3] = true;

	while(!ch.empty())
	{
		int A = 0, B = 0, C = 0;
		vector<pair<int, int> > true_border;
		for(it = ch.begin(); it != ch.end(); it++)
		{
			int a = (*it).first;
			int b = (*it).second;

			for(int c = 1; c <= n; c++)
			{
				if(marc[c] || a == c || b == c || a == b)	continue;

				if(!is_clockwise(a, b, c))
				{
					marc[c] = true;
					A = a, B = b, C = c;
					break;
				}
			}

			if(A)	break;
			else	true_border.push_back((*it)), ans[a] = ans[b] = true, adj[a] = b;// marc[a] = marc[b] = true;
		}

		for(int i = 0; i < true_border.size(); i++)	ch.erase(true_border[i]);

		if(A)	ch.insert({A, C}), ch.insert({C, B});
		ch.erase({A, B});
	}

	int bg = 1, cur = 1, sz = 0;
	vector<int> p, p2;
	while(bg <= n && !ans[bg])	bg++;

	p.push_back(bg);
	cur = adj[bg];
	while(cur != bg)	
	{
		p.push_back(cur);
		cur = adj[cur];
	}

	for(int i = 0; i < p.size(); i++)
	{
		while(2 <= sz && !is_clockwise(p2[sz - 2], p2[sz - 1], p[i]))	p2.pop_back(), sz--;
		p2.push_back(p[i]), sz++;
	}

	if(2 <= sz && !is_clockwise(p2[sz - 2], p2[sz - 1], bg))	sz--;

	give_answer(sz);

/*
	int qtt = 0;
	for(int i = 1; i <= n; i++)	qtt += ans[i];

	give_answer(qtt);
*/
}

Compilation message (stderr)

tri.cpp: In function 'int main()':
tri.cpp:67:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |   for(int i = 0; i < true_border.size(); i++) ch.erase(true_border[i]);
      |                  ~~^~~~~~~~~~~~~~~~~~~~
tri.cpp:85:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |  for(int i = 0; i < p.size(); i++)
      |                 ~~^~~~~~~~~~

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