Submission #576327

#	Time	Username	Problem	Language	Result	Execution time	Memory
576327		timmyfeng	Paint (COI20_paint)	C++17	0 / 100	1069 ms	524288 KiB

paint

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

const int DELTA_I[] = {0, 1, 0, -1}, DELTA_J[] = {-1, 0, 1, 0};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

	freopen("in.txt", "r", stdin);

	int n, m; cin >> n >> m;

	vector<int> color(n * m);
	for (auto &i : color) cin >> i;

	vector<unordered_map<int, unordered_set<int>>> neighbors(n * m);
	vector<vector<int>> members(n * m);
	vector<int> leader(n * m);

	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < m; ++j) {
			int id = i * m + j;
			leader[id] = id;
			members[id].push_back(id);
			for (int dir = 0; dir < 4; ++dir) {
				int i_new = i + DELTA_I[dir], j_new = j + DELTA_J[dir];
				if (0 <= i_new && i_new < n && 0 <= j_new && j_new < m) {
					neighbors[id][color[i_new * m + j_new]].insert(i_new * m + j_new);
				}
			}
		}
	}

	auto update = [&](int a) {
		for (auto &[c, c_neighbors] : neighbors[a]) {
			for (auto b : c_neighbors) {
				neighbors[b][color[a]].insert(a);
			}
		}
	};

	auto merge = [&](int a, int b) {
		if (members[a].size() < members[b].size()) swap(a, b);

		for (auto i : members[b]) leader[i] = a;

		members[a].insert(members[a].end(), members[b].begin(), members[b].end());
		members[b].clear();

		for (auto &[c, c_neighbors] : neighbors[b]) {
			for (auto i : c_neighbors) {
				if (leader[i] == i && color[i] == c)
					neighbors[a][c].insert(i);
			}
		}
		neighbors[b].clear();
	};

	auto fill = [&](int a, int c) {
		a = leader[a];
		while (!neighbors[a][c].empty()) {
			int b = *neighbors[a][c].begin();
			neighbors[a][c].erase(b);
			if (a != b && leader[b] == b && color[b] == c) {
				merge(a, b);
				a = leader[a];
			}
		}
		color[a] = c;
		neighbors[a].erase(c);
		update(a);
	};

	for (int i = 0; i < n * m; ++i)
		fill(i, color[i]);

	int q; cin >> q;

	while (q--) {
		int i, j, c; cin >> i >> j >> c; --i, --j;
		fill(i * m + j, c);
	}

	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < m; ++j) {
			cout << color[leader[i * m + j]] << " ";
		}
		cout << "\n";
	}
}

Compilation message (stderr)

paint.cpp: In function 'int main()':
paint.cpp:10:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |  freopen("in.txt", "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 9
• Subtask 3: 0 / 31
• Subtask 4: 0 / 52