Submission #867769

#	Time	Username	Problem	Language	Result	Execution time	Memory
867769		BoopyTheNoob	Tracks in the Snow (BOI13_tracks)	C++17	97.81 / 100	421 ms	133984 KiB

tracks

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

int main (void) {
    iostream::sync_with_stdio(false);
	cin.tie(0);
    int dx[4]{1, -1, 0, 0};
    int dy[4]{0, 0, 1, -1};
    int N, M;
    cin >> N >> M;
    //vector<string> grid(N);
    string grid[4000];
    for (int i = 0; i < N; i++)
        cin >> grid[i];
    //vector<vector<int>> dist(N, vector<int>(M, 0));
    int dist[4000][4000];
    deque<pair<int, int>> bfs;
    bfs.push_back({0, 0});
    dist[0][0] = 1;
    int ans = 0;
    while (!bfs.empty()) {
        int x = bfs.front().first, y = bfs.front().second;
        bfs.pop_front();
        ans = max(ans, dist[x][y]);
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            /*if (nx < 0 || nx >= N || ny < 0 || ny >= M)
                continue;
            if (dist[nx][ny] != 0 || grid[nx][ny] == '.')
                continue;
            pair<int, int> next = {nx, ny};
            if (grid[x][y] != grid[nx][ny]) {
                dist[nx][ny] = dist[x][y] + 1;
                bfs.push_back({nx, ny});
            } else {
                dist[nx][ny] = dist[x][y];
                bfs.push_front({nx, ny});
            }*/
            if (nx >= 0 && nx < N && ny >= 0 && ny < M && grid[nx][ny] != '.' && dist[nx][ny] == 0) {
                if (grid[nx][ny] != grid[x][y]) {
                    dist[nx][ny] = dist[x][y] + 1;
                    bfs.push_back({nx, ny});
                } else {
                    dist[nx][ny] = dist[x][y];
                    bfs.push_front({nx, ny});
                }
            }
        }
    }
    /*for (auto x: dist) {
        for (auto y: x) {
            cout << y << " ";
        }
        cout << endl;
    }*/
    cout << ans << endl;
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 67.8125 / 70