Problem p03383 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for (ll i = (a); i > (b); --i)
#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOREACH(x, a) for (auto &(x) : (a))
#define VECCIN(x)                                                              \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define bitcnt(x) __builtin_popcount(x)
#define lbit(x) __builtin_ffsll(x)
#define rbit(x) __builtin_clzll(x)
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()

template <typename T = long long> inline T IN() {
  T x;
  cin >> x;
  return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&...tail) {
  cin >> head;
  CIN(move(tail)...);
}
#define CCIN(...)                                                              \
  char __VA_ARGS__;                                                            \
  CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
  double __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
  ll __VA_ARGS__;                                                              \
  CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
  string __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define Yes(a) cout << (a ? "Yes" : "No") << "\n"
#define YES(a) cout << (a ? "YES" : "NO") << "\n"
#define Printv(v)                                                              \
  {                                                                            \
    FOREACH(x, v) { cout << x << " "; }                                        \
    cout << "\n";                                                              \
  }
template <typename T = string> inline void eputs(T s) {
  cout << s << "\n";
  exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}

template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<bool> VB;
typedef vector<double> VD;
typedef vector<string> VS;

const int INF = 1e9;
const int MOD = 1e9 + 7;
// const int MOD = 998244353;
const ll LINF = 1e18;
// const double PI = atan(1.0) * 4.0;
const ll dx[] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dy[] = {0, 1, 1, 1, 0, -1, -1, -1};
#define PI 3.141592653589793238

string S[13];
ll H, W;
ll lp[13];

bool check();
bool dfs(ll);
bool addline();

bool center(ll w, VS b) {
  REP(i, H) if (b[i][w] != b[H - 1 - i][w]) return false;
  return true;
}

bool check() {
  VS b(H);
  VB bused(H);
  REP(i, H) {
    if (bused[lp[i]]) {
      b[H - 1 - lp[i]] = S[i];
    } else {
      b[lp[i]] = S[i];
      bused[lp[i]] = true;
    }
  }
  VL wp(W, -1);
  bool odd = W % 2;
  REP(i, W) {
    if (wp[i] != -1)
      continue;
    wp[i] = i;
    bool ok = false;
    REP(ii, W) {
      if (wp[ii] != -1)
        continue;

      ok = true;
      REP(h, H) {
        if (b[h][i] != b[H - 1 - h][ii]) {
          ok = false;
          break;
        }
      }
      if (ok) {
        wp[ii] = i;
        break;
      }
    }
    if (!ok) {
      if (odd) {
        if (!center(i, b))
          return false;
        odd = false;
      } else {
        return false;
      }
    }
  }
  return true;
}

bool addline() {
  H++;
  REP(i, H - 1) {
    S[H - 1] = S[i];
    if (dfs(0))
      return true;
  }
  return false;
}

bool dfs(ll pnum) {
  if (H % 2)
    return addline();
  if (pnum == W / 2)
    return check();
  ll idx1 = -1;
  REP(i, H) {
    if (lp[i] != -1)
      continue;
    lp[i] = pnum;
    idx1 = i;
    break;
  }
  REP(i, H) {
    if (lp[i] != -1)
      continue;
    lp[i] = pnum;
    if (dfs(pnum + 1))
      return true;
    lp[i] = -1;
  }
  lp[idx1] = -1;
  return false;
}

signed main() {
  cin >> H >> W;
  REP(i, H) cin >> S[i];
  Fill(lp, -1);
  cout << (dfs(0) ? "YES" : "NO") << "\n";
}


Fixed submission:
#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for (ll i = (a); i > (b); --i)
#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOREACH(x, a) for (auto &(x) : (a))
#define VECCIN(x)                                                              \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define bitcnt(x) __builtin_popcount(x)
#define lbit(x) __builtin_ffsll(x)
#define rbit(x) __builtin_clzll(x)
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()

template <typename T = long long> inline T IN() {
  T x;
  cin >> x;
  return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&...tail) {
  cin >> head;
  CIN(move(tail)...);
}
#define CCIN(...)                                                              \
  char __VA_ARGS__;                                                            \
  CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
  double __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
  ll __VA_ARGS__;                                                              \
  CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
  string __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define Yes(a) cout << (a ? "Yes" : "No") << "\n"
#define YES(a) cout << (a ? "YES" : "NO") << "\n"
#define Printv(v)                                                              \
  {                                                                            \
    FOREACH(x, v) { cout << x << " "; }                                        \
    cout << "\n";                                                              \
  }
template <typename T = string> inline void eputs(T s) {
  cout << s << "\n";
  exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}

template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<bool> VB;
typedef vector<double> VD;
typedef vector<string> VS;

const int INF = 1e9;
const int MOD = 1e9 + 7;
// const int MOD = 998244353;
const ll LINF = 1e18;
// const double PI = atan(1.0) * 4.0;
const ll dx[] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dy[] = {0, 1, 1, 1, 0, -1, -1, -1};
#define PI 3.141592653589793238

string S[13];
ll H, W;
ll lp[13];

bool check();
bool dfs(ll);
bool addline();

bool center(ll w, VS b) {
  REP(i, H) if (b[i][w] != b[H - 1 - i][w]) return false;
  return true;
}

bool check() {
  VS b(H);
  VB bused(H);
  REP(i, H) {
    if (bused[lp[i]]) {
      b[H - 1 - lp[i]] = S[i];
    } else {
      b[lp[i]] = S[i];
      bused[lp[i]] = true;
    }
  }
  VL wp(W, -1);
  bool odd = W % 2;
  REP(i, W) {
    if (wp[i] != -1)
      continue;
    wp[i] = i;
    bool ok = false;
    REP(ii, W) {
      if (wp[ii] != -1)
        continue;

      ok = true;
      REP(h, H) {
        if (b[h][i] != b[H - 1 - h][ii]) {
          ok = false;
          break;
        }
      }
      if (ok) {
        wp[ii] = i;
        break;
      }
    }
    if (!ok) {
      if (odd) {
        if (!center(i, b))
          return false;
        odd = false;
      } else {
        return false;
      }
    }
  }
  return true;
}

bool addline() {
  H++;
  REP(i, H - 1) {
    S[H - 1] = S[i];
    if (dfs(0))
      return true;
  }
  return false;
}

bool dfs(ll pnum) {
  if (H % 2)
    return addline();
  if (pnum == H / 2)
    return check();
  ll idx1 = -1;
  REP(i, H) {
    if (lp[i] != -1)
      continue;
    lp[i] = pnum;
    idx1 = i;
    break;
  }
  REP(i, H) {
    if (lp[i] != -1)
      continue;
    lp[i] = pnum;
    if (dfs(pnum + 1))
      return true;
    lp[i] = -1;
  }
  lp[idx1] = -1;
  return false;
}

signed main() {
  cin >> H >> W;
  REP(i, H) cin >> S[i];
  Fill(lp, -1);
  cout << (dfs(0) ? "YES" : "NO") << "\n";
}