// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
int N,S;
string M[1001];
struct node {
int hd;
int md;
int hop;
};
bool v[1001][1001];
node all[1001][1001];
pair<int,int> m;
bool work(int e) {
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
all[i][j].md = -1;
}
}
queue<pair<int,int> > q;
q.push(m);
all[m.first][m.second].md = e;
all[m.first][m.second].hop = 0;
if (all[m.first][m.second].hd != -1 && all[m.first][m.second].hd <= e) return false;
while (!q.empty()) {
auto c = q.front();
//cout << "handling " << c.first << "/" << c.second << "/" << all[c.first][c.second].md << endl;
int cost = all[c.first][c.second].md+1;
q.pop();
queue<tuple<int,int,int> > tq;
tq.push(make_tuple(c.first,c.second,0));
while (!tq.empty()) {
auto tc = tq.front();
//cout << " tq " << get<0>(tc) << "/" << get<1>(tc) << "/" << get<2>(tc) << endl;
tq.pop();
int hop = get<2>(tc)+1;
if (hop > S) continue;
for (auto i : {-1,1}) {
for (int j = 0; j <= 1; j++) {
int ti = j ? get<0>(tc) : (get<0>(tc)+i);
int tj = j ? (get<1>(tc)+i) : (get<1>(tc));
if (ti < 0 || ti >= N || tj < 0 || tj >= N) continue;
//cout << " " << ti << "/" << tj << " " << endl;
if (M[ti][tj] == 'T') continue;
if (all[ti][tj].md >= 0 && all[ti][tj].md < cost) continue;
if (all[ti][tj].hd >= 0 && all[ti][tj].hd < cost) continue;
if (M[ti][tj] == 'D') return true;
if (all[ti][tj].md == cost && all[ti][tj].hop <= hop) continue;
if (hop == S && all[ti][tj].hd >= 0 && all[ti][tj].hd == cost) continue;
//cout << " " << ti << "/" << tj << "/" << hop << " passed" << endl;
all[ti][tj].md = cost;
all[ti][tj].hop = hop;
if (all[ti][tj].hd > cost) {
q.push(make_pair(ti,tj));
//cout << " add q " << ti << "/" << tj << "/" << cost << endl;
}
if (hop == S) continue;
tq.push(make_tuple(ti,tj,hop));
}
}
}
/*for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
cout << all[i][j].md << "/" << all[i][j].hop << " ";
}
cout << endl;
}*/
}
return false;
}
int solve() {
int lo = 0, hi = 2*N;
// if none of the values in the range work, return lo - 1
lo--;
while (lo < hi) {
// find the middle of the current range (rounding up)
int mid = lo + (hi - lo + 1) / 2;
//cout << "mid: " << mid << ", " << lo << "/" << hi;
if (work(mid)) {
//cout << " worked" << endl;
// if mid works, then all numbers smaller than mid also work
lo = mid;
} else {
//cout << " not work" << endl;
// if mid does not work, greater values would not work either
hi = mid - 1;
}
}
return lo;
}
int main() {
cin >> N >> S;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
all[i][j].hd = -1;
}
}
queue<pair<int,int> > q;
for (int i = 0; i < N; i++) {
cin >> M[i];
for (int j = 0; j < N; j++) {
if (M[i][j] == 'H') {
all[i][j].hd = 0;
q.push(make_pair(i,j));
} else if (M[i][j] == 'M') {
m = make_pair(i,j);
}
}
}
while (!q.empty()) {
auto c = q.front();
int cost = all[c.first][c.second].hd+1;
q.pop();
for (auto i : {-1,1}) {
for (int j = 0; j <= 1; j++) {
int ti = j ? c.first : c.first+i;
int tj = j ? c.second+i : c.second;
if (ti < 0 || ti >= N || tj < 0 || tj >= N) continue;
if (M[ti][tj]=='T' || M[ti][tj]=='D' (all[ti][tj].hd!=-1 && all[ti][tj].hd<=cost)) continue;
all[ti][tj].hd = cost;
q.push(make_pair(ti,tj));
//cout << "add " << ti << "/" << tj << endl;
}
}
}
/*for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
cout << all[i][j].hd << " ";
}
cout << endl;
}*/
int r = solve();
cout << r << endl;
//cout << work(2) << endl;
}
Compilation message
mecho.cpp: In function 'int main()':
mecho.cpp:125:85: error: expression cannot be used as a function
125 | if (M[ti][tj]=='T' || M[ti][tj]=='D' (all[ti][tj].hd!=-1 && all[ti][tj].hd<=cost)) continue;
| ^
