제출 #350362

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
350362		Kevin_Zhang_TW	낙하산 고리들 (IOI12_rings)	C++17	100 / 100	2507 ms	232432 KiB

rings

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T L, T R) { while (L != R) cerr << *L << " \n"[next(L) == R], ++L; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

const int MAX_N = 1000005;

int N, glob;

struct dsu {
	vector<int> g, sz, deg;

	int n, badcnt, allbad, answer;

	dsu() {};
	dsu (int n, int size) : n(n), answer(size), badcnt(0), allbad(0) { 
		deg = g = vector<int>(n);
		sz = vector<int>(n, 1);
		iota(AI(g), 0); 
	}

	int F(int i) { return i == g[i] ? i : g[i] = F(g[i]); }

	void M(int a, int b) { 

		if (max(++deg[a], ++deg[b]) >= 3) allbad = true;

		if (allbad) return;

		a = F(a), b = F(b);
		if (sz[a] < sz[b]) swap(a, b);

		if (a != b) {
			return sz[a] += sz[b], g[b] = a, void();
		}
		if (++badcnt == 2) allbad = true;
		// merging into a ring
		// which means you have to remove objects on the ring
		// all of them is ok, since max deg is 2
		// I only care when max deg is <= 2
		// and a ring cannot merge with other for max deg <= 2
		answer = sz[a];
	}
	bool noring() { return badcnt == 0 && allbad == false; }

	int getans() { 
		return allbad ? 0 : answer;
	}
};

dsu alld, forone;

vector<int> edge[MAX_N];

bool iscan[MAX_N];

vector<int> big, can;

vector<dsu> forcan;

void canpush(int id) { if (iscan[id]) return; iscan[id] = true, can.pb(id); }

void Init(int N_) {
	N = N_;
	glob = N;
	alld = dsu(N, N);
}

vector<pair<int,int>> alledge;
int over = -1;
void makebig() {
	static int lst = 0;
	if (lst == 0)
		forone = dsu(N, N-1);
	while (lst < alledge.size()) {
		auto [a, b] = alledge[lst++];
		if (a != over && b != over)
			forone.M(a, b);
	}
}
void superbig(int id) {
	if (over == -1) {
		over = id;
		return;
	}
	else if (over != id) {
		glob = -1;
		return;
	}
}
void adjust(int a, int b) {
	if (glob == -1) return;

	DE(a, b);

	if (big.empty()) {
		assert(can.empty());

		alld.M(a, b);

		glob = alld.getans();

		return;
	}

 	// deal with old ones
 	int oldsize = can.size();
 	for (int i = 0;i < oldsize;++i) {
 		int x = can[i];
 		if (a != x && b != x)
 			forcan[i].M(a, b);
 	}
 
	// put new element into candidate
	for (int x : big) {
		// assert(edge[x].size() <= 3);
		canpush(x);
		for (int u : edge[x]) canpush(u);
	}
	// examine new candidates
 
 	for (int i = oldsize;i < can.size();++i) {
 		forcan.pb(N, N-1);
 		int x = can[i];
 		for (auto [a, b] : alledge) if (a != x && b != x) {
 			forcan[i].M(a, b);
 		}
 	}

	// assert(forcan.size() == can.size());

	glob = 0;

 	// examine all candidates
 	for (int i = 0;i < can.size();++i) 
 		glob += forcan[i].noring();

}
void Link(int A, int B) {
	if (glob == -1) return;

	edge[A].pb(B), edge[B].pb(A);

	if (edge[A].size() == 3) big.pb(A);
	if (edge[B].size() == 3) big.pb(B);

	alledge.pb(A, B);

 	if (edge[A].size() > 3) superbig(A);
 	if (edge[B].size() > 3) superbig(B);

	if (over != -1) return makebig(), void();

 	if (big.size() > 4) {
 		glob = -1;
 		return;
 	}
	
	adjust(A, B);
}

int CountCritical() {
	if (glob == -1) return 0;
	if (over != -1) return forone.noring();
	return max(glob, 0);
}

컴파일 시 표준 에러 (stderr) 메시지

rings.cpp: In constructor 'dsu::dsu(int, int)':
rings.cpp:25:25: warning: 'dsu::answer' will be initialized after [-Wreorder]
   25 |  int n, badcnt, allbad, answer;
      |                         ^~~~~~
rings.cpp:25:9: warning:   'int dsu::badcnt' [-Wreorder]
   25 |  int n, badcnt, allbad, answer;
      |         ^~~~~~
rings.cpp:28:2: warning:   when initialized here [-Wreorder]
   28 |  dsu (int n, int size) : n(n), answer(size), badcnt(0), allbad(0) {
      |  ^~~
rings.cpp: In function 'void makebig()':
rings.cpp:87:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   87 |  while (lst < alledge.size()) {
      |         ~~~~^~~~~~~~~~~~~~~~
rings.cpp: In function 'void adjust(int, int)':
rings.cpp:14:17: warning: statement has no effect [-Wunused-value]
   14 | #define DE(...) 0
      |                 ^
rings.cpp:106:2: note: in expansion of macro 'DE'
  106 |  DE(a, b);
      |  ^~
rings.cpp:134:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  134 |   for (int i = oldsize;i < can.size();++i) {
      |                        ~~^~~~~~~~~~~~
rings.cpp:147:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  147 |   for (int i = 0;i < can.size();++i)
      |                  ~~^~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 14 / 14
• Subtask 5: 31 / 31