#include <bits/stdc++.h>
//#define int long long
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define sc second
#define endl "\n"
#define pii pair<int,int>
using namespace std;
const int MAXN = 4000*4000+5;
const int mod7 = 1e9+7;
const long long inf = 1e9;
vector<vector<pii>> graf(MAXN);
//vector<bool> visited(MAXN);
char val[MAXN];
vector<int> dist(MAXN,inf);
set<pii> pq;
void dfs(int nod)
{
visited[nod] = 1;
pq.insert(mp(0, nod));
dist[nod] = 0;
for(auto x: graf[nod])if(val[nod] == val[x.fi] && !visited[x.fi])dfs(x.fi);
}
void dikstra()
{
while(!pq.empty())
{
auto it = pq.begin();
int u = it -> sc;
pq.erase(it);
for(auto x: graf[u])
{
int nod = x.fi;
int w = x.sc;
if(dist[nod] > dist[u]+w)
{
pq.erase({dist[nod], nod});
dist[nod] = dist[u]+w;
pq.insert({dist[nod], nod});
}
}
}
}
signed main()
{
ios_base::sync_with_stdio(false),cin.tie(0), cout.tie(0);
int tt=1;
//cin >> tt;
while(tt--)
{
int n,m;
cin >> n >> m;
for(int i=0; i<n; i++)
{
string s;cin >> s;
for(int j=0; j<m; j++)
{
val[i*m+j] = s[j];
if(s[j] == '.')continue;
if(i>0 && val[(i-1)*m+j] != '.')
{
graf[i*m+j].pb(mp((i-1)*m+j,val[i*m+j] != val[(i-1)*m+j]));
graf[(i-1)*m+j].pb(mp(i*m+j,val[i*m+j] != val[(i-1)*m+j]));
}
if(j>0 && val[i*m+j-1] != '.')
{
graf[i*m+j].pb(mp(i*m+j-1,val[i*m+j] != val[i*m+j-1]));
graf[i*m+j-1].pb(mp(i*m+j,val[i*m+j] != val[i*m+j-1]));
}
}
}
dfs(0);
dikstra();
int mx = 0;
for(auto x: dist)if(x!=inf)mx = max(mx,x);
cout << mx+1 << endl;
}
}
Compilation message
tracks.cpp: In function 'void dfs(int)':
tracks.cpp:26:5: error: 'visited' was not declared in this scope
26 | visited[nod] = 1;
| ^~~~~~~
