Submission #1247055

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247055		kaiboy	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	498 ms	92932 KiB

tracks

#include <algorithm>
#include <iostream>

using namespace std;

const int    N = 4000;
const int    M = 4000;
const int  INF = 0x3f3f3f3f;
const int di[] = { -1, 1, 0, 0 };
const int dj[] = { 0, 0, -1, 1 };

char cc[N][M + 1];
int dd[N][M], qu[N * M * 2];

int main() {
	ios_base::sync_with_stdio(false), cin.tie(NULL);
	int n, m; cin >> n >> m;
	for (int i = 0; i < n; i++)
		cin >> cc[i];
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			dd[i][j] = INF;
	int cnt = n * m; dd[0][0] = 1, qu[cnt++] = 0;
	for (int h = n * m; h < cnt; h++) {
		int ij = qu[h], i = ij / m, j = ij % m, d = dd[i][j];
		for (int z = 0; z < 4; z++) {
			int i_ = i + di[z], j_ = j + dj[z];
			if (0 <= i_ && i_ < n && 0 <= j_ && j_ < m && cc[i_][j_] != '.') {
				int ij_ = i_ * m + j_;
				if (cc[i][j] == cc[i_][j_]) {
					if (dd[i_][j_] > d)
						dd[i_][j_] = d, qu[h--] = ij_;
				} else {
					if (dd[i_][j_] > d + 1)
						dd[i_][j_] = d + 1, qu[cnt++] = ij_;
				}
			}
		}
	}
	int ans = 0;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++)
			if (cc[i][j] != '.')
				ans = max(ans, dd[i][j]);
	cout << ans << '\n';
	return 0;
}

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