Submission #928496

#	Time	Username	Problem	Language	Result	Execution time	Memory
928496		GrandTiger1729	Maze (JOI23_ho_t3)	C++17	46 / 100	2091 ms	1054960 KiB

Main

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

struct BIT2D
{
    int n, m;
    vector<vector<int>> bit;
    BIT2D(int n_, int m_) : n(n_), m(m_), bit(n + 1, vector<int>(m + 1)) {}
    void add(int i_, int j_, int u)
    {
        for (int i = i_ + 1; i <= n; i += i & -i)
        {
            for (int j = j_ + 1; j <= m; j += j & -j)
            {
                bit[i][j] += u;
            }
        }
    }
    int query(int i_, int j_)
    {
        int ret = 0;
        for (int i = i_; i > 0; i -= i & -i)
        {
            for (int j = j_; j > 0; j -= j & -j)
            {
                ret += bit[i][j];
            }
        }
        return ret;
    }
    int query(int l1, int r1, int l2, int r2)
    {
        return query(l1, l2) + query(r1, r2) - query(l1, r2) - query(r1, l2);
    }
};

const int C = 80, INF = 1e9 + 10;
int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n, m, K;
    cin >> n >> m >> K;
    pair<int, int> A, B;
    cin >> A.first >> A.second >> B.first >> B.second;
    A.first--, A.second--, B.first--, B.second--;
    vector<string> g(n);
    for (int i = 0; i < n; i++)
    {
        cin >> g[i];
    }
    vector<vector<int>> rgt(n, vector<int>(m, -1));
    vector<vector<bool>> vis(n, vector<bool>(m));
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m - 1; j++)
        {
            rgt[i][j] = j + 1;
        }
    }
    auto able = [&](int i, int j)
    {
        return 0 <= i && i < n && 0 <= j && j < m;
    };
    function<int(int, int)> rr = [&](int i, int j) -> int
    {
        if (j == -1 || !vis[i][j])
        {
            return j;
        }
        return rgt[i][j] = rr(i, rgt[i][j]);
    };
    vector<vector<int>> dis(n, vector<int>(m, INF));
    if (K < C)
    {
        vector<pair<int, int>> res;
        res.push_back(A);
        vis[A.first][A.second] = 1;
        dis[A.first][A.second] = 0;
        while (res.size())
        {
            vector<pair<int, int>> res2;
            while (res.size())
            {
                auto [i, j] = res.back();
                res2.emplace_back(i, j);
                res.pop_back();
                for (auto &[dx, dy] : vector<pair<int, int>>{{1, 0}, {0, 1}, {-1, 0}, {0, -1}})
                {
                    if (able(i + dx, j + dy) && !vis[i + dx][j + dy] && g[i + dx][j + dy] == '.')
                    {
                        res.emplace_back(i + dx, j + dy);
                        dis[i + dx][j + dy] = dis[i][j];
                        vis[i + dx][j + dy] = 1;
                        if (vis[B.first][B.second])
                        {
                            goto found;
                        }
                    }
                }
            }
            while (res2.size())
            {
                auto [i, j] = res2.back();
                res2.pop_back();
                for (int ii : {max(0, i - K), min(n - 1, i + K)})
                {
                    int jj = rr(ii, max(0, j - (K - 1)));
                    while (jj != -1 && jj <= j + (K - 1))
                    {
                        res.emplace_back(ii, jj);
                        dis[ii][jj] = dis[i][j] + 1;
                        vis[ii][jj] = 1;
                        jj = rr(ii, max(0, j - (K - 1)));
                        if (vis[B.first][B.second])
                        {
                            goto found;
                        }
                    }
                }
                for (int ii = max(0, i - (K - 1)); ii <= min(n - 1, i + (K - 1)); ii++)
                {
                    int jj = rr(ii, max(0, j - K));
                    while (jj != -1 && jj <= j + K)
                    {
                        res.emplace_back(ii, jj);
                        dis[ii][jj] = dis[i][j] + 1;
                        vis[ii][jj] = 1;
                        jj = rr(ii, max(0, j - K));
                        if (vis[B.first][B.second])
                        {
                            goto found;
                        }
                    }
                }
            }
        }
    }
    else
    {
        BIT2D bit(n, m);
        vector<pair<int, int>> res;
        res.push_back(A);
        vis[A.first][A.second] = 1;
        dis[A.first][A.second] = 0;
        bit.add(A.first, A.second, 1);
        while (res.size())
        {
            int d = dis[res[0].first][res[0].second];
            while (res.size())
            {
                auto [i, j] = res.back();
                res.pop_back();
                for (auto &[dx, dy] : vector<pair<int, int>>{{1, 0}, {0, 1}, {-1, 0}, {0, -1}})
                {
                    if (able(i + dx, j + dy) && !vis[i + dx][j + dy] && g[i + dx][j + dy] == '.')
                    {
                        res.emplace_back(i + dx, j + dy);
                        dis[i + dx][j + dy] = dis[i][j];
                        vis[i + dx][j + dy] = 1;
                        bit.add(i + dx, j + dy, 1);
                        if (vis[B.first][B.second])
                        {
                            goto found;
                        }
                    }
                }
            }
            for (int i = 0; i < n; i++)
            {
                int j = rr(i, 0);
                while (j != -1 && j < m)
                {
                    if (bit.query(max(0, i - K), min(n, i + (K + 1)), max(0, j - K), min(m, j + (K + 1))) \
                        - int(able(i - K, j - K) && vis[i - K][j - K]) \
                        - int(able(i - K, j + K) && vis[i - K][j + K]) \
                        - int(able(i + K, j - K) && vis[i + K][j - K]) \
                        - int(able(i + K, j + K) && vis[i + K][j + K]) > 0)
                    {
                        res.emplace_back(i, j);
                    }
                    j = rr(i, j + 1);
                }
            }
            for (auto &[i, j] : res)
            {
                dis[i][j] = d + 1;
                vis[i][j] = 1;
                bit.add(i, j, 1);
                if (vis[B.first][B.second])
                {
                    goto found;
                }
            }
        }
    }
found:
    int ans = dis[B.first][B.second];
    cout << ans << '\n';
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 19 / 19
• Subtask 3: 0 / 16
• Subtask 4: 19 / 19
• Subtask 5: 0 / 5
• Subtask 6: 0 / 19
• Subtask 7: 0 / 8
• Subtask 8: 0 / 6