Submission #848111

#	Time	Username	Problem	Language	Result	Execution time	Memory
848111		uped	Mecho (IOI09_mecho)	C++14	70 / 100	189 ms	6748 KiB

mecho

#include<bits/stdc++.h>

using namespace std;

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

int main() {
    int n, s;
    cin >> n >> s;
    vector<vector<char>> f(n, vector<char>(n));
    queue<pair<int, int>> q;
    vector<vector<int>> mt(n, vector<int>(n, INT32_MAX));
    pair<int, int> start;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> f[i][j];
            if (f[i][j] == 'M') {
                start = {i, j};
            } else if (f[i][j] == 'H') {
                q.emplace(i, j);
                mt[i][j] = 0;
            }
        }
    }

    auto inside = [&](int i, int j) {
        return i >= 0 && i < n && j >= 0 && j < n && f[i][j] != 'T';
    };
    while (!q.empty()) {
        auto [i, j] = q.front();
        q.pop();
        for (int k = 0; k < 4; ++k) {
            int ni = i + dx[k];
            int nj = j + dy[k];
            if (!inside(ni, nj) || f[ni][nj] == 'D') continue;
            if (mt[i][j] + 1 < mt[ni][nj]) {
                mt[ni][nj] = mt[i][j] + 1;
                q.emplace(ni, nj);
            }
        }
    }

    bool fl = false;
    int l = -1, r = 160000;
    while (r > l + 1) {
        while (!q.empty()) q.pop();
        int mid = (l + r) / 2;
        vector<vector<int>> ms(n, vector<int>(n, INT32_MAX));
        ms[start.first][start.second] = 0;
        bool good = false;
        q.emplace(start.first, start.second);
        while (!q.empty()) {
            auto [i, j] = q.front();
            q.pop();
            for (int k = 0; k < 4; ++k) {
                int ni = i + dx[k];
                int nj = j + dy[k];
                if (!inside(ni, nj)) continue;
                if (f[ni][nj] == 'D') {
                    good = true;
                    fl = true;
                    break;
                }
                int steps = ms[i][j] + 1;
                bool possible = mid + (steps / s) < mt[ni][nj];

                if (possible && steps < ms[ni][nj]) {
                    ms[ni][nj] = steps;
                    q.emplace(ni, nj);
                }
            }
            if (good) break;
        }
        if (good) {
            l = mid;
        } else {
            r = mid;
        }
    }
    cout << l;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:31:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   31 |         auto [i, j] = q.front();
      |              ^
mecho.cpp:54:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   54 |             auto [i, j] = q.front();
      |                  ^
mecho.cpp:44:10: warning: variable 'fl' set but not used [-Wunused-but-set-variable]
   44 |     bool fl = false;
      |          ^~

• Subtask 1: 70 / 100