Submission #543870

#	Time	Username	Problem	Language	Result	Execution time	Memory
543870		timreizin	Mecho (IOI09_mecho)	C++17	73 / 100	228 ms	6888 KiB

mecho

#include <iostream>
#include <vector>
#include <array>
#include <numeric>
#include <cassert>
#include <tuple>
#include <queue>

using namespace std;

using ll = long long;

const int INF = 1e9;

const array<int, 4> dx{1, -1, 0, 0}, dy{0, 0, 1, -1};

bool check(int w, int s, vector<string> &forest, vector<vector<int>> &beeD)
{
    vector<vector<int>> dist(beeD.size(), vector<int>(beeD.size(), INF));
    queue<pair<int, int>> q;
    for (int i = 0; i < beeD.size(); ++i)
    {
        for (int j = 0; j < beeD.size(); ++j)
        {
            if (forest[i][j] == 'M')
            {
                dist[i][j] = 0;
                q.push({i, j});
            }
        }
    }
    while (!q.empty())
    {
        auto [i, j] = q.front();
        q.pop();
        for (int k = 0; k < 4; ++k)
        {
            if (i + dx[k] >= 0 && i + dx[k] < beeD.size() && j + dy[k] >= 0 && j + dy[k] < beeD.size())
            {
                if (dist[i + dx[k]][j + dy[k]] > dist[i][j] + 1 && forest[i + dx[k]][j + dy[k]] != 'T')
                {
                    if (forest[i + dx[k]][j + dy[k]] == 'D')
                    {
                        if (dist[i][j] / s + w < beeD[i + dx[k]][j + dy[k]])
                        {
                            dist[i + dx[k]][j + dy[k]] = dist[i][j] + 1;
                            q.push({i + dx[k], j + dy[k]});
                        }
                    }
                    else
                    {
                        if ((dist[i][j] + 1) / s + w < beeD[i + dx[k]][j + dy[k]])
                        {
                            dist[i + dx[k]][j + dy[k]] = dist[i][j] + 1;
                            q.push({i + dx[k], j + dy[k]});
                        }
                    }
                }
            }
        }
    }
    for (int i = 0; i < beeD.size(); ++i) for (int j = 0; j < beeD.size(); ++j) if (forest[i][j] == 'D') return dist[i][j] != INF;
    return false;
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n, s;
    cin >> n >> s;
    vector<string> forest(n);
    for (string &i : forest) cin >> i;
    vector<vector<int>> beeD(n, vector<int>(n, INF));
    queue<pair<int, int>> q;
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            if (forest[i][j] == 'H')
            {
                beeD[i][j] = 0;
                q.push({i, j});
            }
        }
    }
    while (!q.empty())
    {
        auto [i, j] = q.front();
        q.pop();
        for (int k = 0; k < 4; ++k)
        {
            if (i + dx[k] >= 0 && i + dx[k] < n && j + dy[k] >= 0 && j + dy[k] < n)
            {
                if (beeD[i + dx[k]][j + dy[k]] > beeD[i][j] + 1 && forest[i + dx[k]][j + dy[k]] != 'T')
                {
                    beeD[i + dx[k]][j + dy[k]] = beeD[i][j] + 1;
                    q.push({i + dx[k], j + dy[k]});
                }
            }
        }
    }
    int l = 0, r = n * n;
    while (l < r)
    {
        int m = (l + r) >> 1;
        if (check(m, s, forest, beeD)) l = m + 1;
        else r = m;
    }
    cout << l - 1;
    return 0;
}

/*
7 3
TTTTTTT
TGGGGGT
TGGGGGT
MGGGGGD
TGGGGGT
TGGGGGT
TGHHGGT
*/

Compilation message (stderr)

mecho.cpp: In function 'bool check(int, int, std::vector<std::__cxx11::basic_string<char> >&, std::vector<std::vector<int> >&)':
mecho.cpp:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     for (int i = 0; i < beeD.size(); ++i)
      |                     ~~^~~~~~~~~~~~~
mecho.cpp:23:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |         for (int j = 0; j < beeD.size(); ++j)
      |                         ~~^~~~~~~~~~~~~
mecho.cpp:38:45: warning: comparison of integer expressions of different signedness: 'std::tuple_element<0, std::pair<int, int> >::type' {aka 'int'} and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |             if (i + dx[k] >= 0 && i + dx[k] < beeD.size() && j + dy[k] >= 0 && j + dy[k] < beeD.size())
      |                                   ~~~~~~~~~~^~~~~~~~~~~~~
mecho.cpp:38:90: warning: comparison of integer expressions of different signedness: 'std::tuple_element<1, std::pair<int, int> >::type' {aka 'int'} and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |             if (i + dx[k] >= 0 && i + dx[k] < beeD.size() && j + dy[k] >= 0 && j + dy[k] < beeD.size())
      |                                                                                ~~~~~~~~~~^~~~~~~~~~~~~
mecho.cpp:62:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for (int i = 0; i < beeD.size(); ++i) for (int j = 0; j < beeD.size(); ++j) if (forest[i][j] == 'D') return dist[i][j] != INF;
      |                     ~~^~~~~~~~~~~~~
mecho.cpp:62:61: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for (int i = 0; i < beeD.size(); ++i) for (int j = 0; j < beeD.size(); ++j) if (forest[i][j] == 'D') return dist[i][j] != INF;
      |                                                           ~~^~~~~~~~~~~~~

• Subtask 1: 73 / 100