제출 #787067

#제출 시각아이디문제언어결과실행 시간메모리
787067Yell0Love Polygon (BOI18_polygon)C++17
25 / 100
120 ms16988 KiB
#include <bits/stdc++.h> using namespace std; const int MN=1e5+2; int N,pa[MN],ans=0; vector<pair<string,string>> edges; map<string,int> mp; bool vis[MN]; int main() { ios::sync_with_stdio(0);cin.tie(0); cin>>N; if(N%2) { cout<<"-1\n"; return 0; } for(int i=1;i<=N;++i) { pair<string,string> p; cin>>p.first>>p.second; mp[p.first]=i; edges.push_back(p); } for(int i=0;i<N;++i) pa[mp[edges[i].first]]=mp[edges[i].second]; for(int u=1;u<=N;++u) { if(vis[u]) continue; int v=u,sz=0; while(!vis[v]) { vis[v]=1; ++sz; v=pa[v]; } if(sz==2) continue; ans+=sz/2+sz%2; } cout<<ans<<'\n'; return 0; }
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