Submission #829772

#	Time	Username	Problem	Language	Result	Execution time	Memory
829772		Darren0724	Love Polygon (BOI18_polygon)	C++17	0 / 100	156 ms	9272 KiB

polygon

#include<bits/stdc++.h>
using namespace std;
const int N=100005;
map<string,int> m;
vector<int> vis(N);
vector<int> v(N),in(N);
int cnt=0;
int id(string s){
    if(m.count(s)){
        return m[s];
    }
    int p=m.size();
    m[s]=p;
    return p;
}

void dfs(int k){
    vis[k]=1;
    cnt++;
    if(!vis[v[k]]){
        dfs(v[k]);
    }
}
int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;cin>>n;
    if(n&1){
        cout<<-1<<endl;
        return 0;
    }
    for(int i=0;i<n;i++){
        string a,b;cin>>a>>b;
        v[id(a)]=id(b);
        in[id(b)]++;
    }
    int ans=0;
    for(int i=0;i<n;i++){
        if(!vis[i]&&v[v[i]]==i){
            vis[i]=1;
            vis[v[i]]=1;
        }
    }
    for(int i=0;i<n;i++){
        if(in[i]==0){
            cnt=0;
            dfs(i);
            ans+=(cnt+1)/2;
        }
    }
    cout<<ans<<endl;

    return 0;
}

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