Submission #794523

#	Time	Username	Problem	Language	Result	Execution time	Memory
794523		hugo_pm	Virus Experiment (JOI19_virus)	C++17	100 / 100	677 ms	34524 KiB

virus

#include <bits/stdc++.h>
#define int long long
using namespace std;

#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define sz(v) ((int)((v).size()))

template<typename T>
void chmax(T &x, const T &v) { if (x < v) x = v; }
template<typename T>
void chmin(T &x, const T &v) { if (x > v) x = v; }

using pii = pair<int, int>;
using vi = vector<int>;

string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
	bool first = true;
	string res = "[";
	for (const auto &x : v) {
		if (!first)
			res += ", ";
		first = false;
		res += to_string(x);
	}
	res += "]";
	return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
	cout << ' ' << to_string(H);
	dbg_out(T...);
}

#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

const int MAX_THRESHOLD = 1e5 + 5; // U
const int MAX_DIM = 805;
const int MAX_CASE = MAX_DIM * MAX_DIM;
int M, R, C;
string meteo;
int U[MAX_DIM][MAX_DIM];

int numero(int l, int c) {
	return l*C + c;
}

pii ligCol(int cell) {
	return {cell/C, cell % C};
}
int drepr[MAX_CASE], dsz[MAX_CASE];
void init() {
	rep(i, 0, R*C) {
		drepr[i] = i;
		dsz[i] = 1;
	}
}
int find(int a) {
	if (drepr[a] == a) return a;
	return drepr[a] = find(drepr[a]);
}

void unite(int parent, int child) {
	parent = find(parent), child = find(child);
	if (parent == child) return;
	drepr[child] = parent;
	dsz[parent] += dsz[child];
}

int mapChar[256];
int bestSeg[1 << 4];
void calcSeg() {
	rep(mask, 0, 16) {
		int best = 0, cur = 0;
		for (char c : meteo) {
			if ((1 << mapChar[c]) & mask) {
				++cur;
			} else {
				cur = 0;
			}
			chmax(best, cur);
		}
		if (best >= M) best = MAX_THRESHOLD;
		bestSeg[mask] = best;
	}
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> M >> R >> C;
	cin >> meteo;
	meteo.append(meteo);
	mapChar['N'] = 0, mapChar['W'] = 1, mapChar['E'] = 2, mapChar['S'] = 3;
	vector<int> deltas(256);
	deltas['N'] = C, deltas['S'] = -C; // l*C + c
	if (C > 1) {
		deltas['W'] = 1, deltas['E'] = -1;
	}
	calcSeg();
	// rep(mask, 0, 16) {
	// 	dbg(mask, bestSeg[mask]);
	// }
	rep(i, 0, R) rep(j, 0, C) {
		cin >> U[i][j];
	}
	init();
	priority_queue<pii, vector<pii>, greater<pii>> pq;
	rep(lig, 0, R) rep(col, 0, C) {
		if (U[lig][col] != 0) {
			pq.push({1, numero(lig, col)});
		}
	}

	auto getVoisins = [&] (int cell) {
		vector<int> voisins;
		auto [lig, col] = ligCol(cell);
		rep(dl, -1, 2) rep(dc, -1, 2) if ((dl==0)^(dc==0)) {
			int nl = lig+dl, nc = col+dc;
			if (nl >= 0 && nl < R && nc >= 0 && nc < C && U[nl][nc] != 0) {
				voisins.push_back(numero(nl, nc));
			}
			}
		return voisins;
	};

	int best = 1e9;
	int nbBest = 0;
	auto updAns = [&] (int proposal) {
		if (proposal < best) {
			best = proposal, nbBest = 1;
		} else if (proposal == best) {
			++nbBest;
		}
	};
	vector<int> isInfected(R*C);
	vector<bool> mark(R*C, false);
	int timeInf = 0;
	auto discover = [&] (int depart) {
		int compDepart = find(depart);
		++timeInf;
		queue<int> bfs;
		isInfected[depart] = timeInf;
		for (int v : getVoisins(depart)) {
			bfs.push(v);
		}
		int nbSeen = 1; // compte depart
		while (!bfs.empty()) {
			int cur = bfs.front();
			bfs.pop();
			if (isInfected[cur] == timeInf) continue;
			dbg(depart, "voit"s, cur);
			int mask = 0;
			for (int v : getVoisins(cur)) {
				if (isInfected[v] != timeInf) continue;
				int diff = cur - v;
				char dir = '~';
				for (char c : "NWSE") {
					if (diff == deltas[c]) dir = c;
				}
				assert(dir != '~');
				mask += 1 << mapChar[dir];
			}
			auto [lig, col] = ligCol(cur);
			if (U[lig][col] <= bestSeg[mask]) {
				int compCur = find(cur);
				if (compCur != compDepart) {
					if (mark[compCur]) {
						mark[compDepart] = true;
						return;
					}
					// merge depart dans cur
					unite(cur, depart);
					pq.push({dsz[compCur], compCur});
					return;
				}
				isInfected[cur] = timeInf;
				++nbSeen;
				for (int v : getVoisins(cur)) {
					bfs.push(v);
				}
			}
		}
		// composante stable
		updAns(nbSeen);
		dbg(depart, compDepart, "stable"s);
		mark[compDepart] = true;
	};
	while (!pq.empty()) {
		auto [szCell, cell] = pq.top();
		pq.pop();
		if (szCell != dsz[cell]) continue;
		discover(cell);
	}
	cout << best << '\n';
	cout << nbBest*best << '\n';
}

Compilation message (stderr)

virus.cpp: In function 'void calcSeg()':
virus.cpp:88:22: warning: array subscript has type 'char' [-Wchar-subscripts]
   88 |    if ((1 << mapChar[c]) & mask) {
      |                      ^
virus.cpp: In lambda function:
virus.cpp:174:26: warning: array subscript has type 'char' [-Wchar-subscripts]
  174 |     mask += 1 << mapChar[dir];
      |                          ^~~

• Subtask 1: 14 / 14
• Subtask 2: 6 / 6
• Subtask 3: 80 / 80