| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 886610 | gnu | Mecho (IOI09_mecho) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
int n, S;
vector<string> board;
vector<vector<int>> vis;
vector<int> dx = {1, 0, -1, 0};
vector<int> dy = {0, 1, 0, -1};
struct point{
int i, j;
};
void solve()
{
n, S; cin >> n >> S;
board = vector<string>(n);
vis = vector<vector<int>> (n, vector<int> (n));
for (int i = 0; i < n; ++i) cin >> board[i];
point mecho, home;
vector<point> honey;
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
if (board[i][j] == 'H') honey.emplace_back(i, j);
else if (board[i][j] == 'M') mecho = {i, j};
else if (board[i][j] == 'D') home = {i, j};
}
}
queue<point> mq;
vector<vector<int>> dist(n, vector<int> (n, 0 ));
for (auto x : honey) {
mq.push(x);
vis[x.i][x.j] = 1;
dist[x.i][x.j] = 0;
}
while (!mq.empty()) {
point u = mq.front();
mq.pop();
for (int i = 0; i < 4; ++i) {
if (u.i + dx[i] < 0 || u.i + dx[i] >= n || u.j + dy[i] < 0 || u.j + dy[i] >= n || vis[u.i+dx[i]][u.j+dy[i]] || board[u.i+dx[i]][u.j+dy[i]] == 'T') continue;
mq.emplace(u.i + dx[i], u.j + dy[i]);
vis[u.i + dx[i]][u.j + dy[i]] = 1;
dist[u.i + dx[i]][u.j + dy[i]] = dist[u.i][u.j] + 1;
}
}
// for (auto &x : dist)
// {
// for (auto y : x) cout << y << ' ';
// cout << '\n';
// }
int l = -1, r = 1e9;
// return;
while (l + 1 < r) {
vector<vector<int>> md(n, vector<int> (n));
int m = (l + r) / 2;
vis = vector<vector<int>> (n, vector<int> (n));
queue<point> q;
q.emplace(mecho.i, mecho.j);
vis[mecho.i][mecho.j] = 1;
if (m >= dist[mecho.i][mecho.j]) q.pop();
while (!q.empty()) {
point u = q.front();
q.pop();
for (int i = 0; i < 4; ++i) {
int ni = u.i + dx[i], nj = u.j + dy[i];
if (((md[u.i][u.j]+1) / S >= (dist[u.i][u.j] - m))) continue;
if (u.i + dx[i] < 0 || u.i + dx[i] >= n || u.j + dy[i] < 0 || u.j + dy[i] >= n || vis[u.i+dx[i]][u.j+dy[i]] || board[u.i+dx[i]][u.j+dy[i]] != 'G') continue;
q.emplace(ni, nj);
md[ni][nj] = md[u.i][u.j] + 1;
vis[ni][nj] = 1;
}
}
bool ok = false;
for (int i = 0; i < 4; ++i) {
point u = home;
if (((md[u.i][u.j]+1) / S >= (dist[u.i][u.j] - m))) continue;
if (u.i + dx[i] < 0 || u.i + dx[i] >= n || u.j + dy[i] < 0 || u.j + dy[i] >= n || board[u.i+dx[i]][u.j+dy[i]] != 'G') continue;
if (vis[home.i + dx[i]][home.j+dy[i]]) ok = true;
}
if (ok) {
l = m;
} else r = m;
}
cout << l;
}
int main()
{
ios_base::sync_with_stdio(false); cin.tie(nullptr);
//#ifndef ONLINE_JUDGE
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
//#endif
solve();
}