#include <bits/stdc++.h> #define all(v) begin(v), end(v) #define ii pair<int, int> #define fi first #define se second #define siz(v) (int)(v).size() #define BIT(x, i) (((x) >> (i)) & 1) #define MASK(i) (1LL << (i)) using namespace std; const int MAXN = 805, MAXM = 505, infINT = 1e9 + 234, LOG = 31, mod = 1e9 + 7; const int dx[4] = {-1, +0, +0, +1}; const int dy[4] = {+0, +1, -1, +0}; template<class X, class Y> bool minimize(X &x, const Y &y){return x > y ? x = y, 1: 0;} template<class X, class Y> bool maximize(X &x, const Y &y){return x < y ? x = y, 1: 0;} struct S{ int row, col; bool type; S(int _row = 0, int _col = 0, bool _type = 0): row(_row), col(_col), type(_type) {}; }; int numSize, maxRange, staX, staY, finX, finY, dist[2][MAXN][MAXN]; char board[MAXN][MAXN]; bool bee[MAXN][MAXN]; void input(){ cin >> numSize >> maxRange; for(int row = 1; row <= numSize; row++) for(int col = 1; col <= numSize; col++){ cin >> board[row][col]; if (board[row][col] == 'M') staX = row, staY = col; if (board[row][col] == 'D') finX = row, finY = col; } } bool isValid(int row, int col){ return 1 <= min(row, col) && max(row, col) <= numSize && board[row][col] != 'T'; } void spread(int mid){ queue<ii> q; memset(bee, 0, sizeof bee); for(int row = 1; row <= numSize; row++) for(int col = 1; col <= numSize; col++) if (board[row][col] == 'H') q.emplace(row, col), bee[row][col] = 1; while(mid--){ int sz = siz(q); while(sz--){ int row = q.front().fi, col = q.front().se; q.pop(); for(int k = 0; k < 4; k++){ int nrow = row + dx[k], ncol = col + dy[k]; if (isValid(nrow, ncol) && board[nrow][ncol] == 'G' && !bee[nrow][ncol]){ q.emplace(nrow, ncol), bee[nrow][ncol] = 1; } } } } } int flr(int x){ return (x + maxRange - 1) / maxRange; } bool bfs(int mid){ #define PUSH(row, col, type, d) if (minimize(dist[type][row][col], d)) q.push(S(row, col, type)) queue<S> q; memset(dist, 0x3f, sizeof dist); PUSH(staX, staY, 0, 0); for(int row = 1; row <= numSize; row++) for(int col = 1; col <= numSize; col++) if (bee[row][col]) PUSH(row, col, 1, 0); while(q.size()){ int row = q.front().row, col = q.front().col; bool type = q.front().type; q.pop(); if (type == 0 && row == finX && col == finY) return 1; for(int k = 0; k < 4; k++){ int nrow = row + dx[k], ncol = col + dy[k]; if (isValid(nrow, ncol)){ if (type == 0){ if (flr(dist[0][row][col] + 1) <= dist[1][nrow][ncol]){ PUSH(nrow, ncol, type, dist[type][row][col] + 1); } }else{ if (board[nrow][ncol] == 'G') PUSH(nrow, ncol, type, dist[type][row][col] + 1); } } } } return 0; } bool check(const int &mid){ spread(mid); return bfs(mid); } void solve(){ int l = 0, r = numSize * numSize, m, res = -1; while(l <= r){ m = (l + r) >> 1; if (check(m)) res = m, l = m + 1; else r = m - 1; } cout << res << '\n'; } int main(){ ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); #define task "test" if (fopen(task".inp", "r")){ freopen(task".inp", "r", stdin); freopen(task".out", "w", stdout); } int t = 1; // cin >> t; for(int T = 1; T <= t; T++) { input(); solve(); } cerr << (1.0 * clock()) / CLOCKS_PER_SEC << ".s\n"; }

mecho.cpp: In function 'int main()':
mecho.cpp:130:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:131:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  131 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~