Submission #1026896

#	Time	Username	Problem	Language	Result	Execution time	Memory
1026896		12345678	Love Polygon (BOI18_polygon)	C++17	25 / 100	2047 ms	17464 KiB

polygon

#include <bits/stdc++.h>

using namespace std;

const int nx=1e5+5;

int n, t, vs[nx], l[nx], res, cnt;
string su[nx], sv[nx];
map<string, int> mp;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<=n; i++) cin>>su[i]>>sv[i], mp[su[i]]=mp[sv[i]]=0;
    if (n%2) return cout<<-1, 0;
    for (auto &[x, y]:mp) y=++t;
    for (int i=1; i<=n; i++) l[mp[su[i]]]=mp[sv[i]];
    for (int i=1; i<=n; i++)
    {
        if (vs[i]) continue;
        int sz=1, tmp=i;
        vs[i]=1;
        while (l[tmp]!=i) sz++, tmp=l[tmp], vs[tmp]=1;
        if (sz==2) continue;
        res+=sz/2;
        if (sz%2) cnt++;
    }
    res+=cnt;
    cout<<res;
}

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