Submission #927917

#	Time	Username	Problem	Language	Result	Execution time	Memory
927917		TAhmed33	Love Polygon (BOI18_polygon)	C++98	100 / 100	184 ms	12196 KiB

polygon

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 25;
int p[MAXN], n, deg[MAXN];
map <string, int> d;
bool vis[MAXN];
queue <int> o;
int main () {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n;
	for (int i = 0; i < n; i++) {
		string s, t;
		cin >> s >> t;
		if (!d.count(s)) d[s] = (int)d.size();
		if (!d.count(t)) d[t] = (int)d.size();
		p[d[s]] = d[t];
		deg[d[t]]++;
	}
	if (n & 1) {
		cout << "-1\n";
		return 0;
	}
	int ans = 0;
	for (int i = 0; i < n; i++) if (deg[i] == 0) o.push(i);
	while (!o.empty()) {
		auto k = o.front(); o.pop();
		if (deg[k] != 0) continue;
		if (p[p[k]] != p[k] && p[p[p[k]]] == p[k]) continue;
		if (p[p[k]] == p[k]) {
			p[p[k]] = k;
			deg[k]++; deg[p[k]]--;
			ans++;
			continue;
		}
		ans++;
		deg[p[p[k]]]--;
		if (deg[p[p[k]]] == 0) {
			o.push(p[p[k]]);
		}
		p[p[k]] = k; deg[k]++; 
	}
	for (int i = 0; i < n; i++) {
		if (deg[i] == 0) {
			ans++;
			deg[i] = 2;
			deg[p[i]]--;
		}
	}
	for (int i = 0; i < n; i++) {
		if (deg[i] == 1 && !vis[i]) {
			vector <int> t = {i};
			vis[i] = 1;
			int u = p[i];
			while (u != i) {
				t.push_back(u); vis[u] = 1;
				u = p[u];
			}
			if (t.size() == 2) continue;
			int z = t.size();
			ans += (z >> 1) + (z & 1);
		}
	}
	cout << ans << '\n';
}

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