#include <bits/stdc++.h> using namespace std; using vi = vector<int>; using vvi = vector<vi>; using vvvi = vector<vvi>; using pii = pair<int, int>; using vii = vector<pii>; using vvii = vector<vii>; using l = long long; using vl = vector<l>; using vvl = vector<vl>; using vvvl = vector<vvl>; using pll = pair<l, l>; using vll = vector<pll>; using vvll = vector<vll>; using d = double; using vd = vector<d>; using vvd = vector<vd>; using vvvd = vector<vvd>; using ld = long double; using vld = vector<ld>; using vvld = vector<vld>; using vvvld = vector<vvld>; using vb = vector<bool>; using vvb = vector<vb>; using pbb = pair<bool, bool>; using vbb = vector<pbb>; #define ff first #define ss second #define pb push_back #define eb emplace_back #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() #define sz(x) (int)(x).size() void setIO(string name = "") { ios_base::sync_with_stdio(0); cin.tie(0); if (!name.empty()) { (void)freopen((name + ".in").c_str(), "r", stdin); (void)freopen((name + ".out").c_str(), "w", stdout); } } const ld pi = 3.14159265358979323846; const l LINF = 1e18; const l INF = 1e9; const l MOD = 1e9 + 7; // const l MOD = 998244353; const l MAXN = 2e5 + 5; vi dx = {0, 0, 1, -1}; vi dy = {1, -1, 0, 0}; void solve() { int n, m; cin >> n >> m; vector<string> a(n); for (int i = 0; i < n; ++i) cin >> a[i]; deque<tuple<int, int, int>> q; vvb vis(n, vb(m, false)); q.push_front({0, 0, 0}), vis[0][0] = true; int ans = 0; while (q.size()) { auto [d, x, y] = q.front(); q.pop_front(); ans = max(ans, d); for (int i = 0; i < 4; ++i) { int nx = x + dx[i], ny = y + dy[i]; if (nx < 0 || nx >= n || ny < 0 || ny >= m || vis[nx][ny]) continue; if (a[nx][ny] == '.') continue; if (a[nx][ny] == a[x][y]) q.push_front({d, nx, ny}); else if (a[nx][ny] != a[x][y]) q.push_back({d + 1, nx, ny}); vis[nx][ny] = true; } } cout << ans + 1; } int main() { setIO(""); #ifndef ONLINE_JUDGE // setIO("filename"); #endif int t = 1; // cin >> t; while (t--) solve(); return 0; }

tracks.cpp: In function 'void setIO(std::string)':
tracks.cpp:52:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         (void)freopen((name + ".in").c_str(), "r", stdin);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:53:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |         (void)freopen((name + ".out").c_str(), "w", stdout);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~