Submission #834919

#	Time	Username	Problem	Language	Result	Execution time	Memory
834919		NoLove	Mecho (IOI09_mecho)	C++14	26 / 100	86 ms	9952 KiB

mecho

/**
 *    author : Lăng Trọng Đạt
 *    created: 2023-08-22
**/
#include <bits/stdc++.h>
using namespace std;
#ifndef LANG_DAT
#define db(...) ;
#endif // LANG_DAT
#define int int64_t
#define mp make_pair
#define pb push_back
using pii = pair<int, int>;

const int MAXN = 800 + 5;
int dist[MAXN][MAXN];
char g[MAXN][MAXN];
bool vis[MAXN][MAXN];
int x_change[]{1, -1, 0, 0};
int y_change[]{0, 0, 1, -1};
int n, s;

struct Data {
    int i, j, cnt, k;
    // cnt: number of step, k: : the maximum possible number of minutes that Mecho can continue eating honey at his initial location, while still being able to get home safely.
    // @return number of minutes passed
    int t() {
        return cnt / s;
    }
};

bool vaild1(int i, int j, int d) {
    return 0 <= i && i < n && 0 <= j && j < n &&
           d < dist[i][j] && g[i][j] != 'T' && g[i][j] != 'D';
}
bool vaild2(int i, int j, int d) {
    return 0 <= i && i < n && 0 <= j && j < n &&
           !vis[i][j] && d < dist[i][j] && g[i][j] != 'T';
}

int32_t main() {
    cin.tie(0)->sync_with_stdio(0);
    if (fopen("hi.inp", "r")) {
        freopen("hi.inp", "r", stdin);
//        freopen("hi.out", "w", stdout);
    }

    cin >> n >> s;
    queue<pair<pii, int>> q;
    queue<Data> q2;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++) {
            cin >> g[i][j];
            if (g[i][j] == 'H') {
                q.push({{i, j}, 0});
            } else if (g[i][j] == 'M') {
                q2.push({i, j, 0, n*n});
            }
        }
    memset(dist, 0x3f3f3f, sizeof(dist));
    while (q.size()) {
        auto[p, d] = q.front(); q.pop();
        auto[i, j] = p;
        if (vaild1(i, j, d)) {
            if (g[i][j] == 'D') continue;
            dist[i][j] = d;
            for (int k = 0; k < 4; k++) {
                q.push({{i + x_change[k], j + y_change[k]}, d + 1});
            }
        }
    }

    while (q2.size()) {
        Data x = q2.front(); q2.pop();
        if (vaild2(x.i, x.j, x.t()) && x.k >= 0) {
            vis[x.i][x.j] = true;
            if (g[x.i][x.j] == 'D') {
                cout << x.k;
                return 0;
            }
            if (x.cnt % s == 0 && x.t() == dist[x.i][x.j]) continue;
            x.k = min(x.k, dist[x.i][x.j] - x.t() - (x.cnt % s != 0));
            db(x.i, x.j, x.k, x.t(), x.cnt, dist[x.i][x.j])
            for (int k = 0; k < 4; k++) {
                q2.push({x.i + x_change[k], x.j + y_change[k], x.cnt + 1, x.k});
            }
        }
    }
    cout << -1;
}

Compilation message (stderr)

mecho.cpp: In function 'int32_t main()':
mecho.cpp:62:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   62 |         auto[p, d] = q.front(); q.pop();
      |             ^
mecho.cpp:63:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   63 |         auto[i, j] = p;
      |             ^
mecho.cpp:44:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |         freopen("hi.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 26 / 100