Submission #1175655

#	Time	Username	Problem	Language	Result	Execution time	Memory
1175655		nagornz	Mecho (IOI09_mecho)	C++20	6 / 100	55 ms	21576 KiB

mecho

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,unroll-loops,fast-math,unsafe-math-optimizations")
#define int long long
#define f first
#define s second
#define pii pair <int, int>
#define iShowSpeed cin.tie(NULL)->sync_with_stdio(false)
#define emb emplace_back

using namespace std;

const int inf = 1e14;
const int mod = 998244353;

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

int32_t main(){
    iShowSpeed;
    int n, k; cin >> n >> k;
    char a[n][n];
    for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) cin >> a[i][j];
    vector <vector <int>> bee(n, vector <int> (n, inf)), bear(n, vector <int> (n, inf));
    vector <vector <pii>> prev(n, vector <pii> (n, {-1, -1}));
    queue <pii> q;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (a[i][j] == 'H') bee[i][j] = 0, q.emplace(i, j);
        }
    }
    while (!q.empty()) {
        auto [x, y] = q.front(); q.pop();
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 0 || nx >= n || ny < 0 || ny >= n || bee[nx][ny] <= bee[x][y] + 1) continue;
            q.emplace(nx, ny);
            bee[nx][ny] = bee[x][y] + 1;
        }
    }
    int ex, ey;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (a[i][j] == 'M') bear[i][j] = 0, q.emplace(i, j);
            if (a[i][j] == 'D') ex = i, ey = j;
        }
    }
    while (!q.empty()) {
        auto [x, y] = q.front(); q.pop();
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 0 || nx >= n || ny < 0 || ny >= n || bear[nx][ny] <= bear[x][y] + 1) continue;
            q.emplace(nx, ny);
            bear[nx][ny] = bear[x][y] + 1;
            prev[nx][ny] = {x, y};
        }
    }
    vector <pii> path;
    int curx = ex, cury = ey;
    while (curx != -1 && cury != -1) {
        path.emb(curx, cury);
        int tx = curx, ty = cury;
        curx = prev[tx][ty].f;
        cury = prev[tx][ty].s;
    }
    reverse(path.begin(), path.end());
    path.pop_back();
    // for (auto [x, y] : path) cout << x << " " << y << "\n";
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            // cout << bee[i][j] << " ";
        }
        // cout << "\n";
    }
    // cout << "--------------------\n";
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            bear[i][j] = (bear[i][j] + k - 1) / k;
            // cout << bear[i][j] << " ";
        }
        // cout << "\n";
    }
    int ans = inf;
    for (auto [x, y] : path) {
        ans = min(ans, bee[x][y] - bear[x][y]);
    }
    cout << (ans < 0 ? -1 : ans);
}

• Subtask 1: 6 / 100