Submission #843118

#	Time	Username	Problem	Language	Result	Execution time	Memory
843118		Mizo_Compiler	Tracks in the Snow (BOI13_tracks)	C++17	27.40 / 100	2062 ms	964172 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double ld;
#define pb push_back
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define F first
#define S second
const int N = 4000;
int n, m, ans = 1, sz[N][N];
pair<int, int> p[N][N];
char c[N][N];
bool fc[N][N];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};

void dfs(int i, int j) {
	fc[i][j] = true;
	for (int ii = 0; ii < 4; ii++) {
		int nx = i + dx[ii], ny = j + dy[ii];
		if (nx >= 0 && ny >= 0 && nx < n && ny < m && c[nx][ny] == c[0][0] && !fc[nx][ny]) {
			dfs(nx, ny);
		}
	}
}

pair<int, int> findp(int i, int j) {
	return p[i][j] = (p[i][j].F == i && p[i][j].S == j ? p[i][j] : findp(p[i][j].F, p[i][j].S));
}

void merge(int i, int j, int x, int y) {
	pair<int, int> f = findp(i, j), s = findp(x, y);
	if (f == s)return;
	if (sz[s.F][s.S] > sz[f.F][f.S])swap(f, s);
	p[s.F][s.S] = f;
}

int main () {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> m;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			cin >> c[i][j];
			p[i][j] = {i, j};
			sz[i][j] = 1;
		}
	}
	dfs(0, 0);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
          if (c[i][j] == '.')continue;
			for (int k = 0; k < 4; k++) {
				int nx = i + dx[k], ny = j + dy[k];
				if (nx < 0 || ny < 0 || nx >= n || ny >= m)continue;
				if (c[nx][ny] == c[i][j] || fc[nx][ny]) {
					merge(i, j, nx, ny);
				}
			}
		}
	}
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
          if (c[i][j] == '.')continue;
			if (p[i][j].F == i && p[i][j].S == j) {
				ans++;
			}
		}
	}
	cout << ans;
}

• Subtask 1: 3.3333333333333335 / 30
• Subtask 2: 24.0625 / 70