Submission #862812

#	Time	Username	Problem	Language	Result	Execution time	Memory
862812		maks007	Love Polygon (BOI18_polygon)	C++14	0 / 100	2049 ms	18608 KiB

polygon

//Bismi Allah
#include "bits/stdc++.h"

using namespace std;

signed main () {
	// ios::sync_with_stdio(0);
	// cin.tie(0); cout.tie(0);
	int n, ans = 1e9;
	cin >> n;
	vector <int> who(n, -1), used(n, 0);
	set <int> unused;
	map <string,int> mp;
	function<void(int,int)> f=[&](int v, int cnt) {
		//cout << v << " " << cnt << "\n";
		if(v == 1e9) {
			ans = min(ans, cnt);
			return;
		}
		used[v]=1;
		unused.erase(v);
		for(int i = 0; i < used.size(); i ++) {
			if(!used[i]) {
				used[i]=1;
				unused.erase(i);
				int newcnt = cnt;
				if(who[i] != v) newcnt ++;
				if(who[v] != i) newcnt ++; 
				f(*unused.begin(), newcnt);
				used[i]=0;
				unused.insert(i);
			}
		}
		unused.insert(v);
		used[v]=0;
	};
	int cnt = 0;
	for(int i = 0; i < n; i ++) {
		string u, v;
		cin >> u >> v;
		if(mp.count(u) == 0) mp[u] = mp.size();
		if(mp.count(v) == 0) mp[v] = mp.size();
		if(mp[u] == mp[v]) cnt ++;
		who[mp[u]] = mp[v];
	}
	if(n % 2 == 1) {
		cout << "-1";
		return 0;
	}
	for(int i = 0; i < n; i ++) unused.insert(i);
	unused.insert(1e9);
	f(0,0);
	if(ans == 1e9) cout << "-1";
	else cout << ans;
	return 0;
}

Compilation message (stderr)

polygon.cpp: In lambda function:
polygon.cpp:22:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |   for(int i = 0; i < used.size(); i ++) {
      |                  ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 21
• Subtask 2: 0 / 25
• Subtask 3: 0 / 29
• Subtask 4: 0 / 25