#include <bits/stdc++.h>
using namespace std;
#define MX 4001
typedef long long LL;
typedef pair<int, int> PR;
typedef tuple<int, int, int> TP;
const int MOD = (int)1e9 + 7;
const int INF = (int)1e9 + 5;
const LL MAXV = (LL)1e18;
using vi = vector<int>;
using vii = vector<vi>;
int H, W;
string md[MX]; //snow meadow
/*
use Disjoint Sets to solve the problem.
(1) Use BFS to find all CCs (each with the same footprint letter R or F) and assign each CC with
an integer ID starting from 0.
(2) Perform a scan on the meadow to discover connectitvity between adjcent CCs with different letters
(3) A bipartite graph or tree, then BFS to find the height of the tree which is the answer.
*/
vector<set<int>> adj;
int solve() {
cin >> H >> W;
//read the snow meadow info
for (int i = 0; i < H; i++)
cin >> md[i];
if (md[0][0] == '.')
return 0;
vector<vector<int>> id(H, vector<int>(W, -1));
int t = 0;
for (int i = 0; i < H; i++)
for (int j = 0; j < W; j++) {
if (md[i][j] == '.' || id[i][j] != -1)
continue;
queue<PR> Q;
Q.push({i, j});
id[i][j] = t;
//BFS to find the CC
while (!Q.empty()) {
int r = Q.front().first, c = Q.front().second;
Q.pop();
int dr = 0, dc = 1;
for (int k = 0; k < 4; k++) {
int nr = r + dr, nc = c + dc;
if (nr >= 0 && nr < H && nc >= 0 && nc < W &&
md[nr][nc] == md[i][j] && id[nr][nc] == -1) {
id[nr][nc] = t;
Q.push({nr, nc});
}
swap(dr, dc);
dc = -dc;
}
}
t++;//next CC
}
adj.resize(t);
//scan adjacency between CCs, to build the bipartite graph
for (int i = 0; i < H; i++)
for (int j = 0; j < W; j++) {
if (id[i][j] == -1)
continue;
int dr = 0, dc = 1;
for (int k = 0; k < 4; k++) {
int r = i + dr, c = j + dc;
if (r >= 0 && r < H && c >= 0 && c < W && id[r][c] != -1 && id[r][c] != id[i][j] && md[r][c] != md[i][j]) {
adj[id[i][j]].insert(id[r][c]);
adj[id[r][c]].insert(id[i][j]);
}
swap(dr, dc);
dc = -dc;
}
}
vector<int> d(t, -1);
queue<int> Q2;
Q2.push(0); //the root
d[0] = 1;
while (!Q2.empty()) {
int u = Q2.front();
Q2.pop();
for (auto v : adj[u])
if (d[v] == -1) {
d[v] = d[u]+1;
Q2.push(v);
}
}
return *max_element(d.begin(), d.end());
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin.exceptions(cin.failbit);
cout << solve() << endl;
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
43 ms |
8528 KB |
Output is correct |
| 2 |
Correct |
1 ms |
600 KB |
Output is correct |
| 3 |
Correct |
0 ms |
604 KB |
Output is correct |
| 4 |
Correct |
11 ms |
1628 KB |
Output is correct |
| 5 |
Correct |
4 ms |
2140 KB |
Output is correct |
| 6 |
Correct |
0 ms |
348 KB |
Output is correct |
| 7 |
Correct |
0 ms |
604 KB |
Output is correct |
| 8 |
Correct |
1 ms |
600 KB |
Output is correct |
| 9 |
Correct |
1 ms |
856 KB |
Output is correct |
| 10 |
Correct |
5 ms |
2140 KB |
Output is correct |
| 11 |
Correct |
5 ms |
864 KB |
Output is correct |
| 12 |
Correct |
16 ms |
3416 KB |
Output is correct |
| 13 |
Correct |
4 ms |
2140 KB |
Output is correct |
| 14 |
Correct |
4 ms |
2140 KB |
Output is correct |
| 15 |
Correct |
30 ms |
8220 KB |
Output is correct |
| 16 |
Correct |
42 ms |
8444 KB |
Output is correct |
| 17 |
Correct |
22 ms |
7768 KB |
Output is correct |
| 18 |
Correct |
11 ms |
1772 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 2 |
Correct |
109 ms |
40052 KB |
Output is correct |
| 3 |
Correct |
585 ms |
303184 KB |
Output is correct |
| 4 |
Correct |
140 ms |
58192 KB |
Output is correct |
| 5 |
Correct |
898 ms |
696132 KB |
Output is correct |
| 6 |
Correct |
1511 ms |
162380 KB |
Output is correct |
| 7 |
Correct |
2 ms |
1368 KB |
Output is correct |
| 8 |
Correct |
2 ms |
1624 KB |
Output is correct |
| 9 |
Correct |
5 ms |
1884 KB |
Output is correct |
| 10 |
Correct |
1 ms |
860 KB |
Output is correct |
| 11 |
Correct |
1 ms |
1116 KB |
Output is correct |
| 12 |
Correct |
3 ms |
2140 KB |
Output is correct |
| 13 |
Correct |
107 ms |
40116 KB |
Output is correct |
| 14 |
Correct |
66 ms |
23636 KB |
Output is correct |
| 15 |
Correct |
52 ms |
26032 KB |
Output is correct |
| 16 |
Correct |
60 ms |
18772 KB |
Output is correct |
| 17 |
Correct |
298 ms |
103512 KB |
Output is correct |
| 18 |
Correct |
268 ms |
100148 KB |
Output is correct |
| 19 |
Correct |
143 ms |
58192 KB |
Output is correct |
| 20 |
Correct |
139 ms |
68428 KB |
Output is correct |
| 21 |
Correct |
423 ms |
180052 KB |
Output is correct |
| 22 |
Correct |
894 ms |
696148 KB |
Output is correct |
| 23 |
Correct |
579 ms |
199252 KB |
Output is correct |
| 24 |
Correct |
397 ms |
262484 KB |
Output is correct |
| 25 |
Correct |
1323 ms |
410852 KB |
Output is correct |
| 26 |
Correct |
493 ms |
62032 KB |
Output is correct |
| 27 |
Correct |
626 ms |
83320 KB |
Output is correct |
| 28 |
Correct |
1508 ms |
162392 KB |
Output is correct |
| 29 |
Correct |
1310 ms |
128892 KB |
Output is correct |
| 30 |
Correct |
1083 ms |
113232 KB |
Output is correct |
| 31 |
Execution timed out |
2066 ms |
337344 KB |
Time limit exceeded |
| 32 |
Correct |
569 ms |
100948 KB |
Output is correct |
