Submission #433614

#	Time	Username	Problem	Language	Result	Execution time	Memory
433614		AmineTrabelsi	Love Polygon (BOI18_polygon)	C++14	0 / 100	202 ms	11468 KiB

polygon

#include "bits/stdc++.h"
using namespace std;
// Hi 
const int Mx = 1e5+5;
struct DSU{
    int n;
    vector<int> parent,sz;
    DSU(int _n){
        n = _n;
        for(int i=0;i<=n;i++){
            parent.push_back(i);
            sz.push_back(1);
        }
    }
    int find(int x){
        return parent[x] = (parent[x] == x ? x : find(parent[x]));
    }
    void unite(int a,int b){
        a = find(a);
        b = find(b);
        if(a != b){
            if(sz[a] >= sz[b]){
                parent[b] = a;
                sz[a] += sz[b];
            }else{
                parent[a] = b;
                sz[b] += sz[a];
            }
        }
    }
};
int main(){
    ios::sync_with_stdio(0);cin.tie(0);
    int n;
    cin>>n;
    DSU st(n);
    vector<int> go(n);
    map<string,int> mp;
    int nxt = 0;
    for(int i=0;i<n;i++){
        string s,t;
        cin>>s>>t;
        int first = 0,second = 0;
        if(mp.find(s) != mp.end()){
            first = mp[s];
        }else{
            first = nxt;
            mp[s] = nxt++;
        }
        if(mp.find(t) != mp.end()){
            second = mp[t];
        }else{
            second = nxt;
            mp[t] = nxt++;
        }
        go[first] = second;
        st.unite(first,second);
    }
    
    if(n&1){
        cout << -1 << '\n';
        return 0;
    }
    int ans = 0;
    vector<int> si;
    for(int i=0;i<n;i++){
        if(st.find(i) == i){
            if(st.sz[i] & 1)ans++;
            ans += st.sz[i]/2;
        }
    }
    int cnt = 0;
    for(int i=0;i<n;i++){
        if(go[go[i]] == i && go[i] != i)cnt++;
        if(go[i] == i)ans++;
    }
    ans -= cnt/2;
    cout << ans << '\n';
    return 0;
}

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