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wormhole.cpp
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wormhole.cpp
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/*
ID: ...
TASK: wormhole
LANG: C++
*/
/* LANG can be C++11 or C++14 for those more recent releases */
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <climits>
using namespace std;
bool isLoop(vector<int> pairs, int right[12])
{
bool result = false;
int loops[12] = {0};
for (size_t i = 0; i < pairs.size(); ++i) {
if (i % 2 == 0) {
loops[pairs[i]] = pairs[i + 1];
} else {
loops[pairs[i]] = pairs[i - 1];
}
}
for (int i = 0; i < pairs.size() && !result; i++) {
bool passed[12][2] = {false};
passed[i][1] = true;
int current = i;
while (right[current] != -1) {
current = right[current];
if (passed[current][0]) {
result = true;
break;
}
passed[current][0] = true;
current = loops[current];
if (passed[current][1]) {
result = true;
break;
}
passed[current][1] = true;
}
}
return result;
}
void buildCases(vector<int> numbers, vector<int> sol, vector<vector<int>> &cases)
{
if (numbers.size() == 2) {
sol.push_back(numbers[0]);
sol.push_back(numbers[1]);
cases.push_back(sol);
} else {
for (size_t i = 1; i < numbers.size(); ++i) {
vector<int> tmp = sol;
tmp.push_back(numbers[0]);
tmp.push_back(numbers[i]);
vector<int> new_numbers = numbers;
new_numbers.erase(std::remove(new_numbers.begin(), new_numbers.end(), numbers[0]));
new_numbers.erase(std::remove(new_numbers.begin(), new_numbers.end(), numbers[i]));
buildCases(new_numbers, tmp, cases);
}
}
}
int main() {
ofstream fout ("wormhole.out");
ifstream fin ("wormhole.in");
int n;
fin >> n;
int coords[12][2];
for (int i = 0; i < n; ++i) {
fin >> coords[i][0] >> coords[i][1];
}
int right[12];
for (int i = 0; i < 12; ++i) right[i] = -1;
for (int i = 0; i < n; ++i) {
int right_x = INT_MAX;
for (int j = 0; j < n; ++j) {
if (coords[i][1] == coords[j][1] && coords[j][0] > coords[i][0] && coords[j][0] < right_x) {
right_x = coords[j][0];
right[i] = j;
}
}
}
int counter = 0;
std::vector<int> numbers;
for (int i = 0; i < n; ++i) {
numbers.push_back(i);
}
std::vector<vector<int>> cases;
std::vector<int> empty;
buildCases(numbers, empty, cases);
for (size_t i = 0; i < cases.size(); ++i) {
if (isLoop(cases[i], right)) {
counter++;
}
}
fout << counter << endl;
return 0;
}