Submission #206965

#	Time	Username	Problem	Language	Result	Execution time	Memory
206965		E869120	Meetings (JOI19_meetings)	C++14	100 / 100	1704 ms	1068 KiB

meetings

#include "meetings.h"
#include <vector>
#include <algorithm>
using namespace std;

vector<int> G[2009];
vector<int> I, J1, J2;
bool passed[2009];
bool forced[2009];

void dfs(int pos) {
	passed[pos] = true; int cnts = 0;
	for (int i = 0; i < G[pos].size(); i++) {
		if (passed[G[pos][i]] == true) continue;
		dfs(G[pos][i]); cnts++;
	}
	if (cnts == 0) I.push_back(pos);
}

void dfs2(int pos, int to) {
	if (pos == to) { J2 = J1; return; }
	passed[pos] = true;
	for (int i = 0; i < G[pos].size(); i++) {
		if (passed[G[pos][i]] == true) continue;
		J1.push_back(G[pos][i]);
		dfs2(G[pos][i], to);
		J1.pop_back();
	}
}

vector<int> getpath(int u, int v) {
	J1.clear(); J2.clear();
	J1.push_back(u);
	dfs2(u, v);
	return J2;
}

int getlca(int root, vector<pair<int, int>> E) {
	vector<int> cand; I.clear();
	for (int i = 0; i < E.size(); i++) cand.push_back(E[i].first);
	for (int i = 0; i < E.size(); i++) cand.push_back(E[i].second);
	for (int i : cand) G[i].clear();
	for (int i : cand) passed[i] = false;
	for (int i : cand) forced[i] = false;

	for (int i = 0; i < E.size(); i++) {
		G[E[i].first].push_back(E[i].second);
		G[E[i].second].push_back(E[i].first);
	}
	dfs(E[0].first);
	if (G[E[0].first].size() == 1) I.push_back(E[0].first);

	int mi = I.size() / 2;
	for (int i = mi; i < I.size(); i++) {
		int R = Query(root, I[i - mi], I[i]);
		for (int j : cand) passed[j] = false;
		vector<int> C1 = getpath(I[i - mi], R);
		for (int j = 0; j < C1.size() - 1; j++) forced[C1[j]] = true;
		for (int j : cand) passed[j] = false;
		vector<int> C2 = getpath(I[i], R);
		for (int j = 0; j < C2.size() - 1; j++) forced[C2[j]] = true;
	}

	for (int i : cand) {
		if (forced[i] == false) return i;
	}
	return -1;
}

vector<pair<int, int>> dfs(vector<int> A) {
	if (A.size() == 1) {
		return vector<pair<int, int>>{};
	}
	if (A.size() == 2) {
		return vector<pair<int, int>>{make_pair(A[0], A[1])};
	}
	if (A.size() == 3) {
		int R = Query(A[0], A[1], A[2]);
		vector<pair<int, int>> E;
		for (int i : A) { if (i != R) E.push_back(make_pair(i, R)); }
		return E;
	}

	// 重心っぽい頂点を見つける
	int grav = -1;
	while (true) {
		int s = rand() % A.size(), cnt = 0; bool flag = false;
		for (int i = 1; i <= 6; i++) {
			int t = -1, u = -1;
			while (A[s] == t || t == u || A[s] == u) {
				t = A[rand() % A.size()];
				u = A[rand() % A.size()];
			}
			if (Query(A[s], t, u) == A[s]) cnt++;
			if (i == 2 && cnt <= 0) { flag = true; break; }
			if (i == 4 && cnt <= 1) { flag = true; break; }
			if (i == 6 && cnt <= 2) { flag = true; break; }
			//if (i == 8 && cnt <= 3) { flag = true; break; }
		}
		if (flag == false) { grav = s; break; }
	}

	// 重心分解をする
	vector<bool> used(A.size(), 0);
	used[grav] = true; int rem = A.size() - 1;
	vector<vector<int>> centroid;
	while (rem > 0) {
		int p = -1;
		while (p == -1 || used[p] == true) {
			p = rand() % A.size();
		}
		vector<int> cand; cand.push_back(A[p]); used[p] = true; rem--;
		for (int i = 0; i < A.size(); i++) {
			if (used[i] == true || i == p) continue;
			if (Query(A[grav], A[p], A[i]) != A[grav]) { cand.push_back(A[i]); used[i] = true; rem--; }
		}
		centroid.push_back(cand);
	}

	// 復元をする
	vector<pair<int, int>> ans;
	for (vector<int> f : centroid) {
		vector<pair<int, int>> Z = dfs(f);
		for (pair<int, int> i : Z) ans.push_back(i);
		int U = f[0];
		if (Z.size() >= 1) U = getlca(A[grav], Z);
		ans.push_back(make_pair(A[grav], U));
	}
	return ans;
}

void Solve(int N) {
	vector<int> L;
	for (int i = 0; i < N; i++) L.push_back(i);

	vector<pair<int, int>> V = dfs(L);

	for (int i = 0; i < V.size(); i++) {
		if (V[i].first > V[i].second) swap(V[i].first, V[i].second);
		Bridge(V[i].first, V[i].second);
	}
	return;
}

Compilation message (stderr)

meetings.cpp: In function 'void dfs(int)':
meetings.cpp:13:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < G[pos].size(); i++) {
                  ~~^~~~~~~~~~~~~~~
meetings.cpp: In function 'void dfs2(int, int)':
meetings.cpp:23:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < G[pos].size(); i++) {
                  ~~^~~~~~~~~~~~~~~
meetings.cpp: In function 'int getlca(int, std::vector<std::pair<int, int> >)':
meetings.cpp:40:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < E.size(); i++) cand.push_back(E[i].first);
                  ~~^~~~~~~~~~
meetings.cpp:41:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < E.size(); i++) cand.push_back(E[i].second);
                  ~~^~~~~~~~~~
meetings.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < E.size(); i++) {
                  ~~^~~~~~~~~~
meetings.cpp:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = mi; i < I.size(); i++) {
                   ~~^~~~~~~~~~
meetings.cpp:58:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < C1.size() - 1; j++) forced[C1[j]] = true;
                   ~~^~~~~~~~~~~~~~~
meetings.cpp:61:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < C2.size() - 1; j++) forced[C2[j]] = true;
                   ~~^~~~~~~~~~~~~~~
meetings.cpp: In function 'std::vector<std::pair<int, int> > dfs(std::vector<int>)':
meetings.cpp:113:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < A.size(); i++) {
                   ~~^~~~~~~~~~
meetings.cpp: In function 'void Solve(int)':
meetings.cpp:138:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < V.size(); i++) {
                  ~~^~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 10 / 10
• Subtask 3: 12 / 12
• Subtask 4: 71 / 71