Submission #379289

#	Time	Username	Problem	Language	Result	Execution time	Memory
379289		ruadhan	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	1285 ms	182856 KiB

tracks

#include <bits/stdc++.h>
#define pi pair<int, int>
using namespace std;
const int MAXN = 4005, INF = 1e9 + 1;
string grid[MAXN];
int dist[MAXN][MAXN];
bool visited[MAXN][MAXN];
// queue<pi> q;
deque<pi> q;
int n, m, ans = 0;

int main()
{
    cin >> n >> m;
    for (int i = 0; i < n; i++)
        cin >> grid[i];

    // for (int i = 0; i < n; i++)
    // {
    //     for (int j = 0; j < m; j++)
    //         cout << grid[i][j];
    //     cout << endl;
    // }
    // cout << endl;

    dist[0][0] = 1;
    // q.push({0, 0});
    q.push_back({0, 0});
    while (!q.empty())
    {
        // for (int i = 0; i < n; i++)
        // {
        //     for (int j = 0; j < m; j++)
        //         cout << dist[i][j] << " ";
        //     cout << endl;
        // }
        // cout << endl;
        // int i = q.front().first, j = q.front().second;
        int i = q.front().first, j = q.front().second;
        q.pop_front();
        visited[i][j] = true;
        ans = max(ans, dist[i][j]);
        if (i + 1 < n && !visited[i + 1][j]) // 1
        {
            if (grid[i + 1][j] == '.')
            {
            }
            else if (grid[i][j] == grid[i + 1][j])
            {
                dist[i + 1][j] = min((dist[i + 1][j] == 0 ? INF : dist[i + 1][j]), dist[i][j]);
                q.push_front({i + 1, j});
            }
            else if (grid[i][j] != grid[i + 1][j])
            {
                dist[i + 1][j] = min((dist[i + 1][j] == 0 ? INF : dist[i + 1][j]), dist[i][j] + 1);
                q.push_back({i + 1, j});
            }
        }
        if (j + 1 < m && !visited[i][j + 1]) // 2
        {
            if (grid[i][j + 1] == '.')
            {
            }
            else if (grid[i][j] == grid[i][j + 1])
            {
                dist[i][j + 1] = min((dist[i][j + 1] == 0 ? INF : dist[i][j + 1]), dist[i][j]);
                q.push_front({i, j + 1});
            }
            else if (grid[i][j] != grid[i][j + 1])
            {
                dist[i][j + 1] = min((dist[i][j + 1] == 0 ? INF : dist[i][j + 1]), dist[i][j] + 1);
                q.push_back({i, j + 1});
            }
        }

        if (i - 1 >= 0 && !visited[i - 1][j]) // 3
        {
            if (grid[i - 1][j] == '.')
            {
            }
            else if (grid[i][j] == grid[i - 1][j])
            {
                dist[i - 1][j] = min((dist[i - 1][j] == 0 ? INF : dist[i - 1][j]), dist[i][j]);
                q.push_front({i - 1, j});
            }
            else if (grid[i][j] != grid[i - 1][j])
            {
                dist[i - 1][j] = min((dist[i - 1][j] == 0 ? INF : dist[i - 1][j]), dist[i][j] + 1);
                q.push_back({i - 1, j});
            }
        }
        if (j - 1 >= 0 && !visited[i][j - 1]) // 4
        {
            if (grid[i][j - 1] == '.')
            {
            }
            else if (grid[i][j] == grid[i][j - 1])
            {
                dist[i][j - 1] = min((dist[i][j - 1] == 0 ? INF : dist[i][j - 1]), dist[i][j]);
                q.push_front({i, j - 1});
            }
            else if (grid[i][j] != grid[i][j - 1])
            {
                dist[i][j - 1] = min((dist[i][j - 1] == 0 ? INF : dist[i][j - 1]), dist[i][j] + 1);
                q.push_back({i, j - 1});
            }
        }
    }
    cout << ans << endl;
    return 0;
}

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