Submission #1229462

#	Time	Username	Problem	Language	Result	Execution time	Memory
1229462		chikien2009	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	536 ms	132512 KiB

tracks

#include <bits/stdc++.h>

using namespace std;

void setup()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int dx[4] = {0, 0, -1, 1};
int dy[4] = {1, -1, 0, 0};

int h, w, f[4000][4000], a, b, res, x, y;
string s[4000];
bool check[4000][4000];
deque<pair<int, int>> dq;

int main()
{
    setup();

    cin >> h >> w;
    for (int i = 0; i < h; ++i)
    {
        cin >> s[i];
        for (int j = 0; j < w; ++j)
        {
            f[i][j] = 1e9;
        }
    }
    dq.push_back({0, 0});
    f[0][0] = 1;
    while (!dq.empty())
    {
        a = dq.front().first;
        b = dq.front().second;
        dq.pop_front();
        if (check[a][b])
        {
            continue;
        }
        check[a][b] = true;
        res = max(res, f[a][b]);
        for (int i = 0; i < 4; ++i)
        {
            x = a + dx[i];
            y = b + dy[i];
            if (0 <= x && x < h && 0 <= y && y < w && !check[x][y] && s[x][y] != '.')
            {
                if (f[x][y] > f[a][b] + (s[x][y] != s[a][b]))
                {
                    f[x][y] = f[a][b] + (s[x][y] != s[a][b]);
                    if (s[x][y] != s[a][b])
                    {
                        dq.push_back({x, y});
                    }
                    else
                    {
                        dq.push_front({x, y});
                    }
                }
            }
        }
    }
    cout << res;
    return 0;
}

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