Submission #676522

#	Time	Username	Problem	Language	Result	Execution time	Memory
676522		vjudge1	Love Polygon (BOI18_polygon)	C++17	25 / 100	112 ms	12668 KiB

polygon

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a, b) for (int i=(a); i<(b); i++)
#define REP(i, n) FOR(i, 0, n)
#define REP1(i, n) FOR(i, 1, n+1)
#define pii pair<int, int>
#define SZ(x) (int)((x).size())
#define ALL(x) (x).begin(), (x).end()
#define f first
#define s second
#define pb push_back
#define endl '\n'
 
const ll maxn = 1e5+5;
const ll inf = (1ll<<60);
vector<int> graph(maxn);
vector<bool> occ(maxn);
int dfs(int x){
    if (occ[graph[x]]==0) {
        occ[graph[x]]=1;
        return dfs(graph[x])+1;
    }
    else return 1;
}
signed main(){
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int n; cin>>n;
 
    vector<string> pos(n);
    vector<pair<string, string> > Graph(n);
    REP(i, n){
        cin>>Graph[i].f>>Graph[i].s;
        pos[i]=Graph[i].f;
    }
    sort(ALL(pos));
    REP(i, n){
        int a=upper_bound(ALL(pos), Graph[i].f)-pos.begin();
        int b=upper_bound(ALL(pos), Graph[i].s)-pos.begin();
        graph[a]=b;
    }
    int ans=0;
    REP1(i, n){
        if (occ[i]) continue;
        occ[i]=1;
        int ret=dfs(i);
        if (ret!=2) ans+=ret/2+ret%2;
    }
    if (n%2==1) ans=-1;
    cout<<ans<<endl;
}
 

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