#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 4e3 + 2;
int a[N][N], c[N][N], n, m, iden;
bool Can(int x, int y) {return 0 <= x && x < n && 0 <= y && y < m && c[x][y] == -1;}
void Dfs(int i, int j) {
c[i][j] = iden;
if (Can(i - 1, j) && a[i - 1][j] == a[i][j]) Dfs(i - 1, j);
if (Can(i, j - 1) && a[i][j - 1] == a[i][j]) Dfs(i, j - 1);
if (Can(i + 1, j) && a[i + 1][j] == a[i][j]) Dfs(i + 1, j);
if (Can(i, j + 1) && a[i][j + 1] == a[i][j]) Dfs(i, j + 1);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> m;
for (int i = 0; i < n; i++) {
string s; cin >> s;
for (int j = 0; j < m; j++) {
c[i][j] = -1;
if (s[j] == 'F') a[i][j] = 1;
if (s[j] == 'R') a[i][j] = 2;
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (c[i][j] == -1 && a[i][j] > 0) {
Dfs(i, j);
iden += 1;
}
}
}
vector<set<int>> g(iden);
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (c[i][j] == -1) continue;
if (i < n - 1 && c[i + 1][j] != c[i][j] && c[i + 1][j] != -1) {
g[c[i][j]].push_back(c[i + 1][j]);
g[c[i + 1][j]].push_back(c[i][j]);
}
if (j < m - 1 && c[i][j + 1] != c[i][j] && c[i][j + 1] != -1) {
g[c[i][j]].push_back(c[i][j + 1]);
g[c[i][j + 1]].push_back(c[i][j]);
}
}
}
vector<int> dist(iden, 1e9);
queue<int> q;
dist[0] = 0;
q.push(0);
while (!q.empty()) {
int s = q.front(); q.pop();
for (int u : g[s]) {
if (dist[u] > dist[s] + 1) {
dist[u] = dist[s] + 1;
q.push(u);
}
}
}
int ans = 0;
for (int i = 0; i < iden; i++) {
smax(ans, dist[i] + 1);
}
cout << ans << en;
return 0;
}
Compilation message
tracks.cpp: In function 'int main()':
tracks.cpp:45:28: error: '__gnu_cxx::__alloc_traits<std::allocator<std::set<int> >, std::set<int> >::value_type' {aka 'class std::set<int>'} has no member named 'push_back'
45 | g[c[i][j]].push_back(c[i + 1][j]);
| ^~~~~~~~~
tracks.cpp:46:32: error: '__gnu_cxx::__alloc_traits<std::allocator<std::set<int> >, std::set<int> >::value_type' {aka 'class std::set<int>'} has no member named 'push_back'
46 | g[c[i + 1][j]].push_back(c[i][j]);
| ^~~~~~~~~
tracks.cpp:49:28: error: '__gnu_cxx::__alloc_traits<std::allocator<std::set<int> >, std::set<int> >::value_type' {aka 'class std::set<int>'} has no member named 'push_back'
49 | g[c[i][j]].push_back(c[i][j + 1]);
| ^~~~~~~~~
tracks.cpp:50:32: error: '__gnu_cxx::__alloc_traits<std::allocator<std::set<int> >, std::set<int> >::value_type' {aka 'class std::set<int>'} has no member named 'push_back'
50 | g[c[i][j + 1]].push_back(c[i][j]);
| ^~~~~~~~~
