Submission #1123279

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123279		lucaskojima	Tracks in the Snow (BOI13_tracks)	C++20	0 / 100	2101 ms	177724 KiB

tracks

#include <bits/stdc++.h>
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()

using namespace std;
using ll = long long;
using pii = pair<int, int>;

const char nl = '\n';
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const int INF = 0x3f3f3f3f;

int main() {
	ios::sync_with_stdio(0), cin.tie(0);

	int n, m; cin >> n >> m;
	
	vector<vector<char>> ma(n + 1, vector<char>(m + 1));
	for (int i = 1; i <= n; i++) {
		string s; cin >> s; s = '0' + s;
		for (int j = 1; j <= m; j++) {
			ma[i][j] = s[j];
		}
	}

	using T = pair<int, pii>;
	priority_queue<T, vector<T>, greater<T>> pq;
	vector<vector<int>> dist(n + 1, vector<int>(m + 1, INF));

	pq.push({1, {1, 1}}); dist[1][1] = 1;

	vector<int> dx = {-1, 1, 0, 0};
	vector<int> dy = {0, 0, -1, 1};

	auto ok = [&](int x, int y) -> bool {
		return 1 <= x && x <= n && 1 <= y && y <= m && ma[x][y] != '.';
	};

	while (!pq.empty()) {
		auto [d, v] = pq.top(); pq.pop();
		auto [x, y] = v;
		if (dist[x][y] != d) continue;

		for (int d = 0; d < 4; d++) {
			int nx = x + dx[d];
			int ny = y + dy[d];
			if (!ok(nx, ny)) continue;

			int dd = (ma[x][y] == ma[nx][ny] ? 0 : 1);
			if (d + dd < dist[nx][ny]) {
				dist[nx][ny] = d + dd;
				pq.push({dist[nx][ny], {nx, ny}});
			}
		}
	}

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

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70