Submission #716508

#	Time	Username	Problem	Language	Result	Execution time	Memory
716508		ajab_01	Love Polygon (BOI18_polygon)	C++17	0 / 100	205 ms	13740 KiB

polygon

#include<bits/stdc++.h>
using namespace std;
 
const int N = 1e5 + 5;
vector<int> g[N];
map<string , int> mp;
int ans , n , num;
bool deg[N] , vis[N] , ch = 1;
 
int main(){
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n;
	for(int i = 0 ; i < n ; i++){
		string a , b;
		cin >> a >> b;
		if(mp.find(a) == mp.end()) mp[a] = num++;
		if(mp.find(b) == mp.end()) mp[b] = num++;
		g[mp[a]].push_back(mp[b]);
		deg[mp[b]] = 1;
	}
	if(n & 1){
		cout << -1 << '\n';
		return 0;
	}
 
	for(int i = 0 ; i < n ; i++)
		ch &= deg[i];
 
	if(ch){
		vector<int> vec;
		for(int i = 1 ; i <= n ; i++){
			int len = 0 , ver = i;
			while(!vis[ver]){
				len++;
				vis[ver] = 1;
				ver = g[ver][0];
			}
			if(len == 2) continue;
			vec.push_back(len);
		}
 
		int cnt = 0;
		for(int i : vec){
			ans += i / 2;
			if(i & 1) cnt++;
		}
		ans += cnt - 1;
		cout << ans << '\n';
	}
	return 0;
}

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