Submission #1196258

#	Time	Username	Problem	Language	Result	Execution time	Memory
1196258		marcus06	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	581 ms	110816 KiB

tracks

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

#ifdef LOCAL
#include </home/marcus06/mycp/Library/debug.h>
#else
#define debug(...) 
#endif

const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};

void solve() {
    int H, W;
    cin >> H >> W;

    vector g(H, vector <char> (W));
    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            cin >> g[i][j];
        }
    }

    auto inside = [&](int u, int v) -> bool {
        return (u >= 0 && v >= 0 && u < H && v < W);
    };

    vector depth(H, vector <int> (W));
    deque <pair <int, int>> dq;
    depth[0][0] = 1;
    dq.emplace_back(0, 0);

    int ans = 0;
    while (!dq.empty()) {
        auto [x, y] = dq.front(); dq.pop_front();
        ans = max(ans, depth[x][y]);

        for (int i = 0; i < 4; ++i) {
            int u = x + dx[i], v = y + dy[i];

            if (inside(u, v) && g[u][v] != '.' && depth[u][v] == 0) {
                depth[u][v] = depth[x][y];

                if (g[u][v] == g[x][y]) {
                    dq.emplace_front(u, v);
                } else {
                    depth[u][v] += 1;
                    dq.emplace_back(u, v);
                }
            }
        }
    }

    cout << ans << '\n';
}

int main() {
    std::cin.tie(0)->sync_with_stdio(0);
#ifdef LOCAL
    auto begin = std::chrono::high_resolution_clock::now();
#endif

    int tt = 1;
    while (tt--) {
        solve();
    }

#ifdef LOCAL
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    std::cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
#endif
    return 0;
}

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