Submission #714838

#	Time	Username	Problem	Language	Result	Execution time	Memory
714838		Sohsoh84	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	833 ms	230440 KiB

tracks

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

#define all(x)			(x).begin(),(x).end()
#define X			first
#define Y			second
#define sep			' '
#define endl			'\n'
#define debug(x)		cerr << #x << ": " <<  x << endl;

const ll MAXN = 4e3 + 10;
const int DX[4] = {0, -1, 0, 1};
const int DY[4] = {-1, 0, 1, 0};

int state[MAXN][MAXN], n, m, dist[MAXN][MAXN];
deque<pll> dq;

inline void update(int i, int j, int d, int td) {
	if (!state[i][j]) return;
	if (d + td < dist[i][j]) {
		dist[i][j] = d + td;
		if (td == 0) dq.push_front({i, j});
		else dq.push_back({i, j});
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			char c;
			cin >> c;
			if (c == 'F') state[i][j] = 1;
			else if (c == 'R') state[i][j] = 2;
		}
	}

	memset(dist, 63, sizeof dist);
	dq.push_back({1, 1});
	dist[1][1] = 0;

	while (!dq.empty()) {
		auto [x, y] = dq.front();
		dq.pop_front();

		int d = dist[x][y];
		for (int f = 0; f < 4; f++) {
			int tx = x + DX[f], ty = y + DY[f];
			update(tx, ty, d, int(state[x][y] != state[tx][ty]));
		}
	}

	int ans = 0;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			if (state[i][j])
				ans = max(ans, dist[i][j]);
	
	cout << ans + 1 << endl;
	return 0;
}

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