Submission #1249209

#TimeUsernameProblemLanguageResultExecution timeMemory
1249209nanh0607Mecho (IOI09_mecho)C++20
100 / 100
180 ms4060 KiB
#include <bits/stdc++.h> #include <cstdlib> using namespace std; using ll = long long; using str = string; using pii = pair<int, int>; using pil = pair<int, ll>; using pll = pair<ll, ll>; using tiii = tuple<int, int, int>; #define FOR(i, l, r) for (int i=l; i<=r; i++) #define FOR2(i, l, r) for (int i=l; i>=r; i--) #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() #define fi first #define se second #define ce cout << endl #define pb push_back #define pf push_front #define pob pop_back #define eb emplace_back #define ep emplace const ll MOD = 998244353; const int INF = 1e9; const int LOG = 60; const double MAX = 1e9; int dx[4] = {-1, 1, 0, 0}; int dy[4] = {0, 0, 1, -1}; char direct[4] = {'U', 'D', 'R', 'L'}; // north, south, east, weast void solve() { int n, k; cin >> n >> k; vector<str> forest(n); pii mecho, home; queue<pii> hive; vector<vector<int>> dist_bee(n, vector<int> (n, INF)); FOR(i, 0, n-1) { cin >> forest[i]; FOR(j, 0, n-1) { if (forest[i][j] == 'M') mecho = {i, j}; else if (forest[i][j] == 'D') home = {i, j}; else if (forest[i][j] == 'H') { hive.ep(i, j); dist_bee[i][j] = 0; } } } function<bool(int x, int y)> inside = [&] (int x, int y) { return x >= 0 && x < n && y >= 0 && y < n && forest[x][y] != 'T'; }; while (!hive.empty()) { auto [x1, y1] = hive.front(); hive.pop(); // cout << x1 << ' ' << y1; ce; FOR(i, 0, 3) { int x2 = x1+dx[i], y2 = y1+dy[i]; if (!inside(x2, y2) || dist_bee[x2][y2] != INF || forest[x2][y2] == 'D') continue; dist_bee[x2][y2] = dist_bee[x1][y1] + k; hive.ep(x2, y2); } } // FOR(i, 0, n-1) { // FOR(j, 0, n-1) cout << dist_bee[i][j] << ' '; ce; // } function<bool(int minute)> bfs = [&] (int minute) { if (minute*k >= dist_bee[mecho.fi][mecho.se]) return false; queue<pair<pii, int>> qe; vector<vector<bool>> vis(n, vector<bool> (n, false)); qe.ep(mecho, minute*k); vis[mecho.fi][mecho.se] = true; while (!qe.empty()) { auto [p, t] = qe.front(); qe.pop(); auto [x1, y1] = p; if (pii{x1, y1} == home) return true; FOR(i, 0, 3) { int x2 = x1+dx[i], y2 = y1+dy[i]; if (!inside(x2, y2) || vis[x2][y2] || t+1 >= dist_bee[x2][y2]) continue; qe.ep(pii{x2, y2}, t+1); vis[x2][y2] = true; } // cout << minute; ce; // FOR(i, 0, n-1) { // FOR(j, 0, n-1) cout << vis[i][j] << ' '; ce; // } ce; } return false; }; int low = -1, high = n*n; while (low < high) { int mid = (low + high + 1)/2; if (bfs(mid)) low = mid; else high = mid - 1; } cout << low; } int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); // freopen("atlarge.in", "r", stdin); // freopen("atlarge.out", "w", stdout); int t = 1; // cin >> t; while (t--) solve(); }
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