Submission #789653

#	Time	Username	Problem	Language	Result	Execution time	Memory
789653		phongcd	Mecho (IOI09_mecho)	C++14	0 / 100	5 ms	404 KiB

mecho

#include <bits/stdc++.h>
#define ll long long
#define ld long  double
#define ull unsigned long long
#define ii pair <int, int>
#define ill pair <ll, ll>
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define file "test"
using namespace std;
const ll N = 8e2 + 2;
const ll MOD = 1e9;
const ll INF = 1e18;
const ll base = 311;
const int BLOCK_SIZE = 2000;
 
int n, s;
ii start, target, d[N][N];
char a[N][N];
int mtime[N][N];
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};

void addstep(ii &a) {
    a.se += 1;
    if (a.se > s) a.fi ++, a.se = 1;
}

bool cmp(ii a, ii b) {
    if (a.fi != b.fi) return a.fi < b.fi;
    return a.se < b.se; 
}

bool check(int x) {
    for (int i = 1; i <= n; i ++)
        for (int j = 1; j <= n; j ++) d[i][j] = {2e9, 0};
    
    queue <ii> h;
    h.push(start);
    d[start.fi][start.se] = {x + 1, 0};

    while (!h.empty()) {
        auto [x, y] = h.front(); h.pop();
        ii res = d[x][y];
        addstep(res);

        for (int j = 0; j <= 3; j ++) {
            int u = x + dx[j];
            int v = y + dy[j];
            if (a[u][v] == 'G' && res.fi <= mtime[u][v] && !cmp(d[u][v], res)) {
                h.push({u, v});
                d[u][v] = res;
            }
        }
    }
    return d[target.fi][target.se].fi != 2e9;
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    #ifndef ONLINE_JUDGE
        freopen(file".inp","r",stdin); freopen(file".out","w",stdout);
    #endif
 
    cin >> n >> s;
    queue <ii> bee;
    for (int i = 1; i <= n; i ++)
        for (int j = 1; j <= n; j ++) {
            cin >> a[i][j]; 
            mtime[i][j] = 2e9;

            if (a[i][j] == 'H') 
                bee.push({i, j}), mtime[i][j] = 0;

            if (a[i][j] == 'M')
                a[i][j] = 'G', start = {i, j};

            if (a[i][j] == 'D') 
                a[i][j] = 'G', target = {i, j};
        }

    while (!bee.empty()) {
        auto [x, y] = bee.front(); bee.pop();
        int res = mtime[x][y] + 1;

        for (int j = 0; j <= 3; j ++) {
            int u = x + dx[j];
            int v = y + dy[j];
            if (a[u][v] == 'G' && mtime[u][v] > res) {
                bee.push({u, v});
                mtime[u][v] = res;
            }
        }
    }

    int l = 1, r = 2e3;
    while (l < r) {
        int mid = l + (r - l + 1) / 2;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    cout << (check(l) ? l : -1);
}
/*
     /\_/\ zzZ
    (= -_-)
    / >u  >u
*/

Compilation message (stderr)

mecho.cpp: In function 'bool check(int)':
mecho.cpp:44:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   44 |         auto [x, y] = h.front(); h.pop();
      |              ^
mecho.cpp: In function 'int main()':
mecho.cpp:84:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   84 |         auto [x, y] = bee.front(); bee.pop();
      |              ^
mecho.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(file".inp","r",stdin); freopen(file".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:63:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(file".inp","r",stdin); freopen(file".out","w",stdout);
      |                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 100