| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 492200 |
2021-12-05T23:38:15 Z |
Evang |
Mecho (IOI09_mecho) |
C++17 |
|
454 ms |
6452 KB |
#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
using pi = pair<int, int>;
using vpi = vector<pi>;
const int N = 805;
int n, s, b[N][N], m[N][N];
int dr[] = {0, 0, -1, 1};
int dc[] = {-1, 1, 0, 0};
char a[N][N]; // the grid
pi st; // the starting position for mecho
vpi h; // locations of all of the bee hives
bool good(int r, int c){ // is cell (r, c) within bounds?
return 0 <= r && r < n && 0 <= c && c < n;
}
bool ok(int t){ // can the answer be t?
memset(b, -1, sizeof b);
memset(m, -1, sizeof m);
queue<pi> q; // all of the current bees' possible locations
for(auto x: h){
q.push(x);
b[x.ff][x.ss] = 0;
}
// the bees "expand" for t seconds
while(!q.empty()){ // bfs
auto[r, c] = q.front();
if(b[r][c]==t)
break;
q.pop();
for(int i = 0; i < 4; ++i){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(good(r2, c2)&&(a[r2][c2]=='M'||a[r2][c2]=='G')&&b[r2][c2]==-1){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
queue<pi> q2; // mecho's possible locations
q2.push(st);
m[st.ff][st.ss] = 0;
int t2 = t;
while(!q2.empty()){
t2++;
// mecho's possible locations "expand" for 1 second (where he can take up to s steps)
while(!q2.empty()){ // bfs
auto[r, c] = q2.front();
if(m[r][c]==(t2-t)*s)
break;
q2.pop();
if(~b[r][c])
continue;
for(int i = 0; i < 4; ++i){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(good(r2, c2)&&b[r2][c2]==-1&&m[r2][c2]==-1&&
(a[r2][c2]=='G'||a[r2][c2]=='D')){
if(a[r2][c2]=='D') // did mecho just find home??
return true; // success!
m[r2][c2] = m[r][c] + 1;
q2.emplace(r2, c2);
}
}
}
// the bees' possible locations "expand" by 1 second
while(!q.empty()){ // bfs
auto[r, c] = q.front();
if(b[r][c]==t2)
break;
q.pop();
for(int i = 0; i < 4; ++i){
int r2 = r + dr[i];
int c2 = c + dc[i];
if(good(r2, c2)&&b[r2][c2]==-1&&(a[r2][c2]=='G'||a[r2][c2]=='M')){
b[r2][c2] = b[r][c] + 1;
q.emplace(r2, c2);
}
}
}
}
return false; // mecho never found home without encountering bees :(
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> s;
for(int i = 0; i < n; ++i)
for(int j = 0; j < n; ++j){
cin >> a[i][j];
if(a[i][j]=='M')
st = {i, j};
else if(a[i][j]=='H')
h.emplace_back(i, j);
}
// binary search (yes this binary search might not be commonly seen, but it's shorter to write)
int ans = -1;
for(int u = int(1e6); u > 0; u /= 2)
while(ans + u <= int(1e6) && ok(ans + u))
ans += u;
cout << ans;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 2 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 3 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 4 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 5 |
Correct |
8 ms |
5324 KB |
Output is correct |
| 6 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 7 |
Correct |
362 ms |
6092 KB |
Output is correct |
| 8 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 9 |
Correct |
5 ms |
5404 KB |
Output is correct |
| 10 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 11 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 12 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 13 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 14 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 15 |
Correct |
7 ms |
5396 KB |
Output is correct |
| 16 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 17 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 18 |
Correct |
5 ms |
5324 KB |
Output is correct |
| 19 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 20 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 21 |
Correct |
6 ms |
5416 KB |
Output is correct |
| 22 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 23 |
Correct |
6 ms |
5432 KB |
Output is correct |
| 24 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 25 |
Correct |
8 ms |
5324 KB |
Output is correct |
| 26 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 27 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 28 |
Correct |
6 ms |
5324 KB |
Output is correct |
| 29 |
Correct |
8 ms |
5324 KB |
Output is correct |
| 30 |
Correct |
7 ms |
5440 KB |
Output is correct |
| 31 |
Correct |
8 ms |
5324 KB |
Output is correct |
| 32 |
Correct |
7 ms |
5324 KB |
Output is correct |
| 33 |
Correct |
44 ms |
5648 KB |
Output is correct |
| 34 |
Correct |
41 ms |
5580 KB |
Output is correct |
| 35 |
Correct |
50 ms |
5580 KB |
Output is correct |
| 36 |
Correct |
50 ms |
5580 KB |
Output is correct |
| 37 |
Correct |
50 ms |
5696 KB |
Output is correct |
| 38 |
Correct |
62 ms |
5580 KB |
Output is correct |
| 39 |
Correct |
75 ms |
5708 KB |
Output is correct |
| 40 |
Correct |
63 ms |
5708 KB |
Output is correct |
| 41 |
Correct |
75 ms |
5708 KB |
Output is correct |
| 42 |
Correct |
80 ms |
5708 KB |
Output is correct |
| 43 |
Correct |
99 ms |
5760 KB |
Output is correct |
| 44 |
Correct |
99 ms |
5708 KB |
Output is correct |
| 45 |
Correct |
84 ms |
5804 KB |
Output is correct |
| 46 |
Correct |
94 ms |
5804 KB |
Output is correct |
| 47 |
Correct |
113 ms |
5708 KB |
Output is correct |
| 48 |
Correct |
117 ms |
5844 KB |
Output is correct |
| 49 |
Correct |
104 ms |
5836 KB |
Output is correct |
| 50 |
Correct |
134 ms |
5836 KB |
Output is correct |
| 51 |
Correct |
125 ms |
5836 KB |
Output is correct |
| 52 |
Correct |
126 ms |
5884 KB |
Output is correct |
| 53 |
Correct |
168 ms |
5896 KB |
Output is correct |
| 54 |
Correct |
154 ms |
5916 KB |
Output is correct |
| 55 |
Correct |
147 ms |
5836 KB |
Output is correct |
| 56 |
Correct |
178 ms |
5928 KB |
Output is correct |
| 57 |
Correct |
169 ms |
5964 KB |
Output is correct |
| 58 |
Correct |
164 ms |
5964 KB |
Output is correct |
| 59 |
Correct |
200 ms |
5968 KB |
Output is correct |
| 60 |
Correct |
172 ms |
5964 KB |
Output is correct |
| 61 |
Correct |
178 ms |
6000 KB |
Output is correct |
| 62 |
Correct |
231 ms |
6012 KB |
Output is correct |
| 63 |
Correct |
306 ms |
6020 KB |
Output is correct |
| 64 |
Correct |
342 ms |
6024 KB |
Output is correct |
| 65 |
Correct |
340 ms |
6012 KB |
Output is correct |
| 66 |
Correct |
448 ms |
6008 KB |
Output is correct |
| 67 |
Correct |
294 ms |
5964 KB |
Output is correct |
| 68 |
Correct |
328 ms |
6040 KB |
Output is correct |
| 69 |
Correct |
303 ms |
5964 KB |
Output is correct |
| 70 |
Correct |
301 ms |
6040 KB |
Output is correct |
| 71 |
Correct |
320 ms |
6044 KB |
Output is correct |
| 72 |
Correct |
454 ms |
6060 KB |
Output is correct |
| 73 |
Correct |
291 ms |
6452 KB |
Output is correct |
| 74 |
Correct |
375 ms |
6304 KB |
Output is correct |
| 75 |
Correct |
389 ms |
6436 KB |
Output is correct |
| 76 |
Correct |
370 ms |
6220 KB |
Output is correct |
| 77 |
Correct |
402 ms |
6440 KB |
Output is correct |
| 78 |
Correct |
302 ms |
6276 KB |
Output is correct |
| 79 |
Correct |
385 ms |
6276 KB |
Output is correct |
| 80 |
Correct |
380 ms |
6268 KB |
Output is correct |
| 81 |
Correct |
338 ms |
6276 KB |
Output is correct |
| 82 |
Correct |
324 ms |
6192 KB |
Output is correct |
| 83 |
Correct |
316 ms |
6220 KB |
Output is correct |
| 84 |
Correct |
365 ms |
6236 KB |
Output is correct |
| 85 |
Correct |
377 ms |
6240 KB |
Output is correct |
| 86 |
Correct |
381 ms |
6220 KB |
Output is correct |
| 87 |
Correct |
358 ms |
6240 KB |
Output is correct |
| 88 |
Correct |
324 ms |
6304 KB |
Output is correct |
| 89 |
Correct |
355 ms |
6092 KB |
Output is correct |
| 90 |
Correct |
360 ms |
6172 KB |
Output is correct |
| 91 |
Correct |
351 ms |
6092 KB |
Output is correct |
| 92 |
Correct |
365 ms |
6172 KB |
Output is correct |
