Submission #1190736

#	Time	Username	Problem	Language	Result	Execution time	Memory
1190736		Abdalaziz_Alshami	Love Polygon (BOI18_polygon)	C++20	0 / 100	403 ms	27060 KiB

polygon

#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
map<string,string>a;
map<string,int>vis;
int dfs(string x){
	vis[x]=1;
	int s=0;
	if(!vis[a[x]]) s=dfs(a[x]);
	return s+1;
}
signed main(){
	ios::sync_with_stdio(0); cin.tie(0);
	int n; cin>>n;
	set<string>s; 
	for(int i=0;i<n;i++){
		string u,v; cin>>u>>v;
		s.insert(u); s.insert(v);
		a[u]=v;
	}
	int ans=0;
	for(auto i:s){
		if(a[i]==i) {
			ans++; continue; 
		}
		if(!vis[i]){
			vis[i]=1;
			ans+=(dfs(i)+1)/2;
		}
	}
	if(n%2) cout<<-1;
	else cout<<ans;
}

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