Submission #687222

#	Time	Username	Problem	Language	Result	Execution time	Memory
687222		stevancv	Mecho (IOI09_mecho)	C++14	100 / 100	206 ms	6944 KiB

mecho

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 800 + 2;
const int inf = 1e9;
string s[N];
int b[N][N], a[N][N], n, k;
int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, -1, 0, 1};
bool Can(int x, int y) {
    if (x < 0 || x >= n) return 0;
    if (y < 0 || y >= n) return 0;
    if (s[x][y] == 'T') return 0;
    return 1;
}
bool Ok(int x, int y, int val, int m) {
    return (b[x][y] - val / k - m) > 0;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    int ii, jj, iii, jjj;
    ii = jj = iii = jjj = -1;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (s[i][j] == 'M') {
                ii = i;
                jj = j;
            }
            if (s[i][j] == 'D') {
                iii = i;
                jjj = j;
            }
        }
    }
    queue<pair<int, int>> q;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (s[i][j] == 'H') {
                q.push({i, j});
                b[i][j] = 0;
            }
            else b[i][j] = inf;
        }
    }
    while (!q.empty()) {
        auto u = q.front(); q.pop();
        for (int i = 0; i < 4; i++) {
            int nx = u.first + dx[i];
            int ny = u.second + dy[i];
            if (!Can(nx, ny) || (nx == iii && ny == jjj)) continue;
            if (b[nx][ny] > b[u.first][u.second] + 1) {
                q.push({nx, ny});
                b[nx][ny] = b[u.first][u.second] + 1;
            }
        }
    }
    auto Moze = [&] (int mid) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                a[i][j] = inf;
            }
        }
        if (mid >= b[iii][jjj]) return false;
        q.push({ii, jj});
        a[ii][jj] = 0;
        while (!q.empty()) {
            auto u = q.front(); q.pop();
            for (int i = 0; i < 4; i++) {
                int nx = u.first + dx[i];
                int ny = u.second + dy[i];
                if (!Can(nx, ny)) continue;
                if (Ok(nx, ny, a[u.first][u.second] + 1, mid) && a[nx][ny] > a[u.first][u.second] + 1) {
                    q.push({nx, ny});
                    a[nx][ny] = a[u.first][u.second] + 1;
                }
            }
        }
        return a[iii][jjj] != inf;
    };
    int l = 0, r = b[ii][jj] - 1, ans = -1;
    while (l <= r) {
        int mid = l + r >> 1;
        if (Moze(mid)) {
            l = mid + 1;
            ans = mid;
        }
        else r = mid - 1;
    }
    cout << ans << en;
    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:92:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   92 |         int mid = l + r >> 1;
      |                   ~~^~~

• Subtask 1: 100 / 100