Submission #467435

#	Time	Username	Problem	Language	Result	Execution time	Memory
467435		Ozy	Love Polygon (BOI18_polygon)	C++17	25 / 100	2094 ms	11824 KiB

polygon

#include <iostream>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i = (a); i <= (b); i++)
#define repa(i,a,b) for(int i = (a); i >= (b); i--)
#define lli long long int
#define debug(a) cout << #a << " = " << a << endl
#define debugsl(a) cout << #a << " = " << a << ", "

#define MAX 100000

string A,B;
lli n,a,b,cont,impares,res;
map<string,lli> mapa;
lli amor[MAX+2],visitados[MAX+2];

lli dfs(lli ini) {

    lli act = amor[ini];
    lli cant = 1;

    visitados[ini] = 1;

    while (act != ini) {
        visitados[act] = 1;
        cant++;
        act = amor[act];
    }

    if (cant == 2) return 0;
    if (cant&1) impares++;
    cant++;
    cant /= 2;
    return cant;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n;

    cont = 1;
    rep(i,1,n) {
        cin >> A >> B;

        if (mapa.find(A) == mapa.end()) mapa[A] = cont++;
        a = mapa[A];
        if (mapa.find(B) == mapa.end()) mapa[B] = cont++;
        b = mapa[B];

        amor[a] = b;
    }

    res = 0;
    impares = 0;
    rep(i,1,n) if (visitados[i] == 0) res += dfs(i);

    if (impares&1) cout << -1;
    else cout << res;
}

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