Submission #772670

#	Time	Username	Problem	Language	Result	Execution time	Memory
772670		marvinthang	Thousands Islands (IOI22_islands)	C++17	100 / 100	259 ms	36520 KiB

islands

/*************************************
*    author: marvinthang             *
*    created: 04.07.2023 16:55:32    *
*************************************/

#include "islands.h"
#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i--; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
		#include "debug.h"
#else
		#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
		#define DB(...) 23
		#define db(...) 23
		#define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }

// end of template

variant <bool, vector <int>> find_journey(int N, int M, vector <int> U, vector <int> V) {
	vector <set <int>> adj(N), radj(N);
	REP(i, M) {
		adj[U[i]].insert(i);
		radj[V[i]].insert(i);
	}
	queue <int> q;
	REP(i, N) if (adj[i].empty()) q.push(i);

	int u = 0;
	vector <int> path;
	while (true) {
		while (!q.empty()) {
			int u = q.front(); q.pop();
			for (int id: radj[u]) {
				adj[U[id]].erase(id);
				if (adj[U[id]].empty()) q.push(U[id]);
			}
			radj[u].clear();
		}
		if (adj[u].empty()) return false;
		if (adj[u].size() == 1) {
			int id = *adj[u].begin();
			int v = V[id];
			path.push_back(id);
			adj[u].erase(id);
			radj[v].erase(id);
			q.push(u);
			u = v;
			continue;
		}
		REP(i, N) while (adj[i].size() > 1 + (i == u)) adj[i].erase(adj[i].begin());
		int cnt_1 = 0;
		vector <int> states(M), cycle;
		do {
			int id = *adj[u].begin();
			adj[u].erase(id);
			if (!cycle.empty()) adj[u].insert(cycle.back());
			cycle.push_back(id);
			u = U[id] ^ V[id] ^ u;
			states[id] ^= 1;
			cnt_1 += states[id] ? 1 : -1;
		} while (cnt_1);
		vector <int> res = path;
		res.insert(res.end(), ALL(cycle));
		res.insert(res.end(), path.rbegin(), path.rend());
		return res;
	}
	return false;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 21 / 21
• Subtask 4: 24 / 24
• Subtask 5: 45 / 45