/*
ID: c4ts0up
LANG: C++
TASK: Mecho
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define ff first
#define ss second
const int NMAX = 805;
const int INF = 1e9;
int n, s;
pair <int,int> home, mecho;
char grid[NMAX][NMAX];
int dist[NMAX][NMAX];
bool seen[NMAX][NMAX];
// hace el check a una coordenada
bool Check(int row, int col) {
return (0 <= row && row < n && 0 <= col && col < n);
}
// BFS para encontrar el tiempo requerido para que las abejas lleguen a un lugar
void EncontrarDistancias() {
queue <pair <int,int> > to;
for (int i=0; i<=n; i++) for (int j=0; j<=n; j++) seen[i][j] = false;
for (int i=0; i<n; i++) for (int j=0; j<n; j++) {
if (grid[i][j] == 'H') to.push({i,j}), dist[i][j] = 0;
else dist[i][j] = INF;
}
while (!to.empty()) {
pair <int,int> curr = to.front();
to.pop();
// ya lo visitamos
if (seen[curr.ff][curr.ss]) continue;
if (grid[curr.ff][curr.ss] == 'T' || grid[curr.ff][curr.ss] == 'D') {
seen[curr.ff][curr.ss] = true;
continue;
}
// visitamos a todos los vecinos
if (Check(curr.ff+1, curr.ss) && dist[curr.ff+1][curr.ss] > dist[curr.ff][curr.ss]+1) to.push({curr.ff+1, curr.ss}), dist[curr.ff+1][curr.ss] = dist[curr.ff][curr.ss]+1;
if (Check(curr.ff-1, curr.ss) && dist[curr.ff-1][curr.ss] > dist[curr.ff][curr.ss]+1) to.push({curr.ff-1, curr.ss}), dist[curr.ff-1][curr.ss] = dist[curr.ff][curr.ss]+1;
if (Check(curr.ff, curr.ss+1) && dist[curr.ff][curr.ss+1] > dist[curr.ff][curr.ss]+1) to.push({curr.ff, curr.ss+1}), dist[curr.ff][curr.ss+1] = dist[curr.ff][curr.ss]+1;
if (Check(curr.ff, curr.ss-1) && dist[curr.ff][curr.ss-1] > dist[curr.ff][curr.ss]+1) to.push({curr.ff, curr.ss-1}), dist[curr.ff][curr.ss-1] = dist[curr.ff][curr.ss]+1;
seen[curr.ff][curr.ss] = true;
}
}
bool BFS(int minutos) {
queue <pair <int, pair <int,int> > > to;
to.push({0, mecho});
for (int i=0; i<=n; i++) for (int j=0; j<=n; j++) seen[i][j] = false;
while (!to.empty()) {
pair <int, pair <int,int> > curr = to.front();
to.pop();
int r = curr.ss.ff;
int c = curr.ss.ss;
int pasos = curr.ff;
//cerr << "Visitando <" << r << ", " << c << "> luego de " << pasos << " pasos (pasos/s = " << (max(pasos, 0)/s) << ")" << endl;
// ya lo visitamos, no tenemos que volver
if (seen[r][c]) continue;
// no podemos atravesarlo
if (grid[r][c] == 'T') {
seen[r][c] = true;
continue;
}
else if (grid[r][c] == 'D') return true;
// ya está infestado de abejas, o sea, bloqueado
if (minutos + (max(pasos, 0)/s) >= dist[r][c]) {
seen[r][c] = true;
continue;
}
// visitamos a todos los vecinos
if (!seen[r+1][c] && Check(r+1, c)) to.push({pasos+1, {r+1,c}});
if (!seen[r-1][c] && Check(r-1, c)) to.push({pasos+1, {r-1,c}});
if (!seen[r][c+1] && Check(r, c+1)) to.push({pasos+1, {r,c+1}});
if (!seen[r][c-1] && Check(r, c-1)) to.push({pasos+1, {r,c-1}});
seen[r][c] = true;
}
return false;
}
int main() {
/*//
freopen("test.in", "r", stdin);
freopen("", "w", stdout);
//*/
cin >> n >> s;
for (int i=0; i<n; i++) {
string aux;
cin >> aux;
for (int j=0; j<n; j++) {
grid[i][j] = aux[j];
if (grid[i][j] == 'M') mecho = {i,j};
else if (grid[i][j] == 'D') home = {i,j};
}
}
EncontrarDistancias();
/*//
for (int i=0; i<n; i++) {
for (int j=0; j<n; j++) {
if (grid[i][j] == 'T' || grid[i][j] == 'D') cerr << grid[i][j] << " ";
else cerr << dist[i][j] << " ";
}
cerr << endl;
}
//*/
if (!BFS(0)) {
cout << -1 << endl;
exit(0);
}
int lb = 0, ub = 1e6, mid;
while (lb <= ub) {
mid = (lb+ub)/2;
//cerr << "--- mid = " << mid << endl;
if (BFS(mid)) lb = mid+1;
else ub = mid-1;
}
//cerr << "lb = " << lb << "; ub = " << ub << "; mid = " << mid << endl;
cout << ub << endl;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
1 ms |
384 KB |
Output is correct |
3 |
Correct |
1 ms |
384 KB |
Output is correct |
4 |
Correct |
1 ms |
384 KB |
Output is correct |
5 |
Correct |
0 ms |
384 KB |
Output is correct |
6 |
Correct |
0 ms |
384 KB |
Output is correct |
7 |
Correct |
171 ms |
4896 KB |
Output is correct |
8 |
Correct |
1 ms |
384 KB |
Output is correct |
9 |
Correct |
1 ms |
384 KB |
Output is correct |
10 |
Correct |
0 ms |
384 KB |
Output is correct |
11 |
Correct |
0 ms |
384 KB |
Output is correct |
12 |
Correct |
1 ms |
640 KB |
Output is correct |
13 |
Correct |
1 ms |
512 KB |
Output is correct |
14 |
Correct |
1 ms |
640 KB |
Output is correct |
15 |
Correct |
0 ms |
384 KB |
Output is correct |
16 |
Correct |
1 ms |
384 KB |
Output is correct |
17 |
Correct |
1 ms |
384 KB |
Output is correct |
18 |
Correct |
1 ms |
384 KB |
Output is correct |
19 |
Correct |
1 ms |
512 KB |
Output is correct |
20 |
Correct |
1 ms |
512 KB |
Output is correct |
21 |
Correct |
1 ms |
512 KB |
Output is correct |
22 |
Correct |
1 ms |
512 KB |
Output is correct |
23 |
Correct |
1 ms |
512 KB |
Output is correct |
24 |
Correct |
1 ms |
512 KB |
Output is correct |
25 |
Correct |
1 ms |
640 KB |
Output is correct |
26 |
Correct |
1 ms |
640 KB |
Output is correct |
27 |
Correct |
1 ms |
640 KB |
Output is correct |
28 |
Correct |
1 ms |
640 KB |
Output is correct |
29 |
Correct |
1 ms |
640 KB |
Output is correct |
30 |
Correct |
1 ms |
640 KB |
Output is correct |
31 |
Correct |
1 ms |
640 KB |
Output is correct |
32 |
Correct |
1 ms |
640 KB |
Output is correct |
33 |
Correct |
10 ms |
2048 KB |
Output is correct |
34 |
Correct |
11 ms |
2048 KB |
Output is correct |
35 |
Correct |
33 ms |
2048 KB |
Output is correct |
36 |
Correct |
14 ms |
2432 KB |
Output is correct |
37 |
Correct |
14 ms |
2304 KB |
Output is correct |
38 |
Correct |
43 ms |
2432 KB |
Output is correct |
39 |
Correct |
17 ms |
2688 KB |
Output is correct |
40 |
Correct |
17 ms |
2688 KB |
Output is correct |
41 |
Correct |
55 ms |
2688 KB |
Output is correct |
42 |
Correct |
21 ms |
2944 KB |
Output is correct |
43 |
Correct |
21 ms |
2944 KB |
Output is correct |
44 |
Correct |
72 ms |
2944 KB |
Output is correct |
45 |
Correct |
24 ms |
3200 KB |
Output is correct |
46 |
Correct |
25 ms |
3200 KB |
Output is correct |
47 |
Correct |
91 ms |
3280 KB |
Output is correct |
48 |
Correct |
29 ms |
3448 KB |
Output is correct |
49 |
Correct |
29 ms |
3456 KB |
Output is correct |
50 |
Correct |
101 ms |
3576 KB |
Output is correct |
51 |
Correct |
34 ms |
3832 KB |
Output is correct |
52 |
Correct |
35 ms |
3840 KB |
Output is correct |
53 |
Correct |
132 ms |
3960 KB |
Output is correct |
54 |
Correct |
39 ms |
4084 KB |
Output is correct |
55 |
Correct |
39 ms |
4096 KB |
Output is correct |
56 |
Correct |
142 ms |
4088 KB |
Output is correct |
57 |
Correct |
44 ms |
4472 KB |
Output is correct |
58 |
Correct |
49 ms |
4472 KB |
Output is correct |
59 |
Correct |
167 ms |
4472 KB |
Output is correct |
60 |
Correct |
50 ms |
4728 KB |
Output is correct |
61 |
Correct |
50 ms |
4728 KB |
Output is correct |
62 |
Correct |
181 ms |
4728 KB |
Output is correct |
63 |
Correct |
170 ms |
4856 KB |
Output is correct |
64 |
Correct |
242 ms |
4856 KB |
Output is correct |
65 |
Correct |
277 ms |
4732 KB |
Output is correct |
66 |
Correct |
235 ms |
4856 KB |
Output is correct |
67 |
Correct |
65 ms |
4728 KB |
Output is correct |
68 |
Correct |
96 ms |
4728 KB |
Output is correct |
69 |
Correct |
93 ms |
4728 KB |
Output is correct |
70 |
Correct |
85 ms |
4728 KB |
Output is correct |
71 |
Correct |
73 ms |
4728 KB |
Output is correct |
72 |
Correct |
65 ms |
4732 KB |
Output is correct |
73 |
Correct |
81 ms |
4984 KB |
Output is correct |
74 |
Correct |
108 ms |
4988 KB |
Output is correct |
75 |
Correct |
117 ms |
4984 KB |
Output is correct |
76 |
Correct |
101 ms |
4984 KB |
Output is correct |
77 |
Correct |
106 ms |
4984 KB |
Output is correct |
78 |
Correct |
60 ms |
4984 KB |
Output is correct |
79 |
Correct |
103 ms |
4984 KB |
Output is correct |
80 |
Correct |
108 ms |
4984 KB |
Output is correct |
81 |
Correct |
114 ms |
4984 KB |
Output is correct |
82 |
Correct |
95 ms |
4984 KB |
Output is correct |
83 |
Correct |
128 ms |
4984 KB |
Output is correct |
84 |
Correct |
132 ms |
4984 KB |
Output is correct |
85 |
Correct |
116 ms |
4984 KB |
Output is correct |
86 |
Correct |
126 ms |
5024 KB |
Output is correct |
87 |
Correct |
119 ms |
4900 KB |
Output is correct |
88 |
Correct |
136 ms |
4984 KB |
Output is correct |
89 |
Correct |
137 ms |
4856 KB |
Output is correct |
90 |
Correct |
140 ms |
4880 KB |
Output is correct |
91 |
Correct |
134 ms |
4856 KB |
Output is correct |
92 |
Correct |
134 ms |
4856 KB |
Output is correct |