Submission #376960

#	Time	Username	Problem	Language	Result	Execution time	Memory
376960		Return_0	Love Polygon (BOI18_polygon)	C++17	54 / 100	142 ms	12156 KiB

polygon

#pragma GCC optimize("Ofast,unroll-loops")
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef int ll;
typedef long double ld;
typedef pair <ll, ll> pll;

#ifdef SINA
#define dbg(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1> void __f(const char* name, Arg1&& arg1) { cout << name << " : " << arg1 << std::endl; }
template <typename Arg1, typename... Args> void __f (const char* names, Arg1&& arg1, Args&&... args) {
	const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...); }
#define dbg2(x, j, n) cout<< #x << " : "; output((j), (n), x, 1); cout.flush();
#else
#define dbg(...) 0
#define dbg2(x, j, n) 0
#endif
#define SZ(x) ((ll)((x).size()))
#define File(s, t) freopen(s ".txt", "r", stdin); freopen(t ".txt", "w", stdout);
#define input(j, n, a) for (int _i = (j); _i < (n)+(j); _i++) cin>> a[_i];
#define output(j, n, a, t) for (int _i = (j); _i < (n)+(j); _i++) cout<< a[_i] << (((t) && _i != (n)+(j)-1)? ' ' : '\n');
#define kill(x) return cout<< (x) << endl, 0
#define cl const ll
#define fr first
#define sc second
#define lc (v << 1)
#define rc (lc | 1)
#define mid ((l + r) >> 1)
#define All(x) (x).begin(), (x).end()

cl inf = sizeof(ll) == 4 ? (1e9 + 10) : (3e18), mod = 1e9 + 7, MOD = 998244353;

template <class A,class B> ostream& operator << (ostream& out,const pair<A,B>&a){return out<<'('<<a.first<<", "<<a.second<<')';}
template <class A> ostream& operator << (ostream& out, const vector<A> &a) {
	out<< '['; for (int i = -1; ++i < int(a.size());) out<< a[i] << (i + 1 < int(a.size()) ? ", " : ""); return out<<']'; }
template <class T, typename _t = less <T> > using Tree = tree <T, null_type, _t, rb_tree_tag, tree_order_statistics_node_update>;

cl N = 1e5 + 7;

ll P [N], n, ans, cnt, lst;
bool mark [N];
unordered_map <string, ll> mp;
string s, t;
priority_queue <pll, vector <pll>, greater <pll>> pq;
ll in [N];

//!
void f () {
	if (cnt == 2) return;
	ans += (cnt >> 1);
	ans += (cnt & 1);
}

void dfs (ll v) {
	mark[v] = 1;
	cnt++;
	if (!mark[P[v]]) dfs(P[v]);
}

void sol1 () {
	for (ll i = 1; i <= n; i++) if (!mark[i]) cnt = 0, dfs(i), f();
}
//*

int main ()
{
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);

	cin>> n; if (n & 1) kill(-1);
	for (ll i = 1; i <= n; i++) {
		cin>> s >> t;
		if (!mp.count(s)) mp[s] = ++lst;
		if (!mp.count(t)) mp[t] = ++lst;
		P[mp[s]] = mp[t];
		in[mp[t]]++;
	}

	for (ll i = 1; i <= n; i++) pq.push({in[i], i});

	while (!pq.empty()) {
		pll x = pq.top();
		pq.pop();
		// dbg(x.fr, x.sc);
		if (x.fr > 0) {
			break;
		}
		if (mark[x.sc]) dbg(x.sc);
		if (x.fr != in[x.sc] || mark[x.sc]) continue;
		// dbg(x, P[x.sc]);
		mark[x.sc] = 1;
		if (P[x.sc] == -1 || mark[P[x.sc]]) {
			ans++;
			continue;
		}

		mark[P[x.sc]] = 1;
		if (P[P[x.sc]] == x.sc) {
			continue;
		}

		ans++;
		in[P[P[x.sc]]]--;
		pq.push({in[P[P[x.sc]]], P[P[x.sc]]});
	}

	// dbg(ans);

	for (ll i = 1; i <= n; i++) {
		if(!mark[i]) {
			// dbg(i);
			cnt = 1;
			mark[i] = 1;
			// dbg(i, P[i]);
			for(int j = P[i]; j != i; j = P[j]) {
				// dbg(j, P[j]);
				cnt++;
				mark[j] = true;
			}
			// dbg(cnt);
			if (cnt == 2) continue;
			ans += (cnt + 1) / 2;
		}
	}

	kill(ans);

	return 0;
}
/*
8
leonard emmy
ada emmy
isaac leonard
emmy pierre
pierre bernhard
bernhard emmy
sofia karl
karl sofia

4
a c
b c
c d
d d

*/

Compilation message (stderr)

polygon.cpp: In function 'int main()':
polygon.cpp:23:18: warning: statement has no effect [-Wunused-value]
   23 | #define dbg(...) 0
      |                  ^
polygon.cpp:95:19: note: in expansion of macro 'dbg'
   95 |   if (mark[x.sc]) dbg(x.sc);
      |                   ^~~

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