Submission #726851

#	Time	Username	Problem	Language	Result	Execution time	Memory
726851		SanguineChameleon	Fun Tour (APIO20_fun)	C++17	100 / 100	253 ms	22184 KiB

fun

#include "fun.h"
#include <bits/stdc++.h>
using namespace std;

pair<int, vector<int>> solve(int N, vector<pair<int, vector<pair<int, int>>>> sub, int root, bool merge_later) {
	int prv = -1;
	vector<int> res;
	int merge_time = -1;
	for (int i = 0; i < N - 1; i++) {
		if (sub[0].second.size() > sub[1].second.size()) {
			swap(sub[0], sub[1]);
		}
		if (sub[1].second.size() > sub[2].second.size()) {
			swap(sub[1], sub[2]);
		}
		if (sub[0].second.size() > sub[2].second.size()) {
			swap(sub[0], sub[2]);
		}
		pair<pair<int, int>, int> best = {{-1, -1}, -1};
		bool will_merge = false;
		if (merge_time == -1 && sub[0].second.size() + sub[1].second.size() <= sub[2].second.size()) {
			will_merge = true;
			merge_time = i;
		}
		if (will_merge && !merge_later) {
			if (prv == sub[0].first || prv == sub[1].first) {
				prv = 0;
			}
			else if (prv == sub[1].first) {
				prv = 0;
			}
			else {
				prv = 1;
			}
			sub[0].first = 0;
			sub[1].first = 0;
			sub[2].first = 1;
		}
		for (int k = 0; k < 2; k++) {
			if (best.second != -1) {
				break;
			}
			for (int j = 0; j < 3; j++) {
				if (k == 0 && prv == sub[j].first) {
					continue;
				}
				if (!sub[j].second.empty()) {
					best = max(best, make_pair(sub[j].second.back(), j));
				}
			}
		}
		res.push_back(sub[best.second].second.back().second);
		sub[best.second].second.pop_back();
		prv = sub[best.second].first;
		if (will_merge && merge_later) {
			if (prv == sub[0].first || prv == sub[1].first) {
				prv = 0;
			}
			else if (prv == sub[1].first) {
				prv = 0;
			}
			else {
				prv = 1;
			}
			sub[0].first = 0;
			sub[1].first = 0;
			sub[2].first = 1;
		}
	}
	res.push_back(root);
	return {merge_time, res};
}

vector<int> createFunTour(int N, int Q) {
	pair<int, int> best = {N + 1, -1};
	for (int i = 0; i < N; i++) {
		int sz = attractionsBehind(0, i);
		if (sz * 2 >= N) {
			best = min(best, {sz, i});
		}
	}
	int root = best.second;
	vector<int> ch;
	vector<int> depth(N);
	for (int i = 0; i < N; i++) {
		depth[i] = hoursRequired(root, i);
		if (depth[i] == 1) {
			ch.push_back(i);
		}
	}
	bool merge = (int)(ch.size()) <= 2;
	ch.resize(3, -1);
	vector<pair<int, vector<pair<int, int>>>> sub(3);
	for (int i = 0; i < 3; i++) {
		sub[i].first = i;
	}
	for (int i = 0; i < N; i++) {
		if (i == root) {
			continue;
		}
		int id = 2;
		for (int j = 0; j < 2; j++) {
			if (hoursRequired(ch[j], i) + 1 == depth[i]) {
				id = j;
				break;
			}
		}
		sub[id].second.push_back({depth[i], i});
	}
	for (int i = 0; i < 3; i++) {
		sort(sub[i].second.begin(), sub[i].second.end());
	}
	auto p = solve(N, sub, root, false);
	int pos = p.first;
	vector<int> res = p.second;
	if (pos == -1) {
		return res;
	}
	int prv = N + 1;
	for (int i = max(0, pos - 5); i < min(N - 1, pos + 5); i++) {
		int cur = hoursRequired(res[i], res[i + 1]);
		if (prv < cur) {
			return solve(N, sub, root, true).second;
		}
		prv = cur;
	}
	return res;
}

Compilation message (stderr)

fun.cpp: In function 'std::vector<int> createFunTour(int, int)':
fun.cpp:91:7: warning: unused variable 'merge' [-Wunused-variable]
   91 |  bool merge = (int)(ch.size()) <= 2;
      |       ^~~~~

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 21 / 21
• Subtask 4: 19 / 19
• Subtask 5: 34 / 34