#include <bits/stdc++.h>
using P = std::pair<int, int>;
const int INF = 1e9;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int32_t main() {
std::ios::sync_with_stdio(0), std::cin.tie(0), std::cout.tie(0);
int N, S; std::cin >> N >> S;
std::vector<std::string> a(N);
P start, end;
std::vector<std::vector<int>> dpB(N, std::vector<int>(N, INF));
std::queue<P> qb;
for(int i = 0; i < N; i++){
std::cin >> a[i];
for(int j = 0; j < N; j++){
if(a[i][j] == 'M'){
start = P(i, j);
a[i][j] = 'G';
}else if(a[i][j] == 'D'){
end = P(i, j);
}else if(a[i][j] == 'H'){
qb.emplace(i, j);
dpB[i][j] = 0;
}
}
}
while(!qb.empty()){
P tp = qb.front(); qb.pop();
for(int i = 0; i < 4; i++){
int nx = tp.first + dx[i];
int ny = tp.second + dy[i];
if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
if(a[nx][ny] == 'G'){
if(dpB[nx][ny] > dpB[tp.first][tp.second] + S){
dpB[nx][ny] = dpB[tp.first][tp.second] + S;
qb.emplace(nx, ny);
}
}
}
}
std::vector<std::vector<int>> dp = dpB;
auto check = [&](int delay) -> bool{
int tickStart = delay * S;
if(tickStart >= dpB[start.first][start.second]) return false;
// can only walk through regions wich tick value less
for(int i = 0; i < N; i++) for(int j = 0; j < N; j++) dp[i][j] = INF;
std::queue<P> q;
q.push(start); dp[start.first][start.second] = tickStart;
while(!q.empty()){
P tp = q.front(); q.pop();
if(tp == end) return true;
for(int i = 0; i < 4; i++){
int nx = tp.first + dx[i];
int ny = tp.second + dy[i];
if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
if(dpB[nx][ny] <= dp[tp.first][tp.second] + 1) continue;
if(a[nx][ny] == 'G' || a[nx][ny] == 'D'){
if(dp[nx][ny] > dp[tp.first][tp.second] + 1){
dp[nx][ny] = dp[tp.first][tp.second] + 1;
q.emplace(nx, ny);
}
}
}
}
return false;
};
if(!check(0)){
std::cout << "-1\n";
return 0;
}
int l = -1, h = 1;
while(check(h)) h *= 2;
while(l < h){
int mid = l + (h - l + 1) / 2;
if(check(mid)){
l = mid;
}else{
h = mid - 1;
}
}
std::cout << l << '\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
304 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
7 |
Correct |
135 ms |
6716 KB |
Output is correct |
8 |
Correct |
0 ms |
204 KB |
Output is correct |
9 |
Correct |
1 ms |
312 KB |
Output is correct |
10 |
Correct |
0 ms |
204 KB |
Output is correct |
11 |
Correct |
0 ms |
204 KB |
Output is correct |
12 |
Correct |
0 ms |
332 KB |
Output is correct |
13 |
Correct |
1 ms |
332 KB |
Output is correct |
14 |
Correct |
1 ms |
312 KB |
Output is correct |
15 |
Correct |
1 ms |
204 KB |
Output is correct |
16 |
Correct |
1 ms |
204 KB |
Output is correct |
17 |
Correct |
0 ms |
312 KB |
Output is correct |
18 |
Correct |
1 ms |
204 KB |
Output is correct |
19 |
Correct |
0 ms |
204 KB |
Output is correct |
20 |
Correct |
1 ms |
204 KB |
Output is correct |
21 |
Correct |
0 ms |
332 KB |
Output is correct |
22 |
Correct |
1 ms |
204 KB |
Output is correct |
23 |
Correct |
0 ms |
332 KB |
Output is correct |
24 |
Correct |
1 ms |
332 KB |
Output is correct |
25 |
Correct |
1 ms |
332 KB |
Output is correct |
26 |
Correct |
1 ms |
332 KB |
Output is correct |
27 |
Correct |
1 ms |
332 KB |
Output is correct |
28 |
Correct |
1 ms |
332 KB |
Output is correct |
29 |
Correct |
1 ms |
332 KB |
Output is correct |
30 |
Correct |
1 ms |
332 KB |
Output is correct |
31 |
Correct |
1 ms |
332 KB |
Output is correct |
32 |
Correct |
1 ms |
332 KB |
Output is correct |
33 |
Correct |
5 ms |
1484 KB |
Output is correct |
34 |
Correct |
5 ms |
1484 KB |
Output is correct |
35 |
Correct |
20 ms |
1556 KB |
Output is correct |
36 |
Correct |
9 ms |
1868 KB |
Output is correct |
37 |
Correct |
7 ms |
1868 KB |
Output is correct |
38 |
Correct |
34 ms |
1868 KB |
Output is correct |
39 |
Correct |
8 ms |
2348 KB |
Output is correct |
40 |
Correct |
9 ms |
2348 KB |
Output is correct |
41 |
Correct |
33 ms |
2320 KB |
Output is correct |
42 |
Correct |
10 ms |
2836 KB |
Output is correct |
43 |
Correct |
11 ms |
2764 KB |
Output is correct |
44 |
Correct |
42 ms |
2764 KB |
Output is correct |
45 |
Correct |
12 ms |
3276 KB |
Output is correct |
46 |
Correct |
12 ms |
3276 KB |
Output is correct |
47 |
Correct |
48 ms |
3328 KB |
Output is correct |
48 |
Correct |
14 ms |
3916 KB |
Output is correct |
49 |
Correct |
15 ms |
3936 KB |
Output is correct |
50 |
Correct |
57 ms |
3860 KB |
Output is correct |
51 |
Correct |
16 ms |
4428 KB |
Output is correct |
52 |
Correct |
22 ms |
4416 KB |
Output is correct |
53 |
Correct |
67 ms |
4428 KB |
Output is correct |
54 |
Correct |
20 ms |
5196 KB |
Output is correct |
55 |
Correct |
20 ms |
5196 KB |
Output is correct |
56 |
Correct |
77 ms |
5192 KB |
Output is correct |
57 |
Correct |
21 ms |
5876 KB |
Output is correct |
58 |
Correct |
23 ms |
5836 KB |
Output is correct |
59 |
Correct |
88 ms |
5916 KB |
Output is correct |
60 |
Correct |
25 ms |
6604 KB |
Output is correct |
61 |
Correct |
28 ms |
6728 KB |
Output is correct |
62 |
Correct |
104 ms |
6696 KB |
Output is correct |
63 |
Correct |
72 ms |
6592 KB |
Output is correct |
64 |
Correct |
381 ms |
6600 KB |
Output is correct |
65 |
Correct |
355 ms |
6692 KB |
Output is correct |
66 |
Correct |
266 ms |
6596 KB |
Output is correct |
67 |
Correct |
31 ms |
6604 KB |
Output is correct |
68 |
Correct |
41 ms |
6600 KB |
Output is correct |
69 |
Correct |
76 ms |
6752 KB |
Output is correct |
70 |
Correct |
55 ms |
6604 KB |
Output is correct |
71 |
Correct |
50 ms |
6596 KB |
Output is correct |
72 |
Correct |
38 ms |
6604 KB |
Output is correct |
73 |
Correct |
47 ms |
6732 KB |
Output is correct |
74 |
Correct |
159 ms |
6632 KB |
Output is correct |
75 |
Correct |
125 ms |
6740 KB |
Output is correct |
76 |
Correct |
116 ms |
6852 KB |
Output is correct |
77 |
Correct |
137 ms |
6732 KB |
Output is correct |
78 |
Correct |
29 ms |
6728 KB |
Output is correct |
79 |
Correct |
157 ms |
6724 KB |
Output is correct |
80 |
Correct |
122 ms |
6728 KB |
Output is correct |
81 |
Correct |
126 ms |
6848 KB |
Output is correct |
82 |
Correct |
132 ms |
6724 KB |
Output is correct |
83 |
Correct |
53 ms |
6732 KB |
Output is correct |
84 |
Correct |
165 ms |
6672 KB |
Output is correct |
85 |
Correct |
128 ms |
6692 KB |
Output is correct |
86 |
Correct |
124 ms |
6732 KB |
Output is correct |
87 |
Correct |
148 ms |
6724 KB |
Output is correct |
88 |
Correct |
57 ms |
6636 KB |
Output is correct |
89 |
Correct |
186 ms |
6604 KB |
Output is correct |
90 |
Correct |
127 ms |
6720 KB |
Output is correct |
91 |
Correct |
154 ms |
6724 KB |
Output is correct |
92 |
Correct |
106 ms |
6716 KB |
Output is correct |