Problem p02943 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template <class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, n) for (int(i) = (a); (i) < (n); ++(i))
#define eFOR(i, a, n) for (int(i) = (a); (i) <= (n); ++(i))
#define rFOR(i, a, n) for (int(i) = (n)-1; (i) >= (a); --(i))
#define erFOR(i, a, n) for (int(i) = (n); (i) >= (a); --(i))
#define each(i, a) for (auto &i : a)
#define SORT(i) sort((i).begin(), (i).end())
#define rSORT(i, a) sort((i).begin(), (i).end(), (a))
#define all(i) (i).begin(), (i).end()
#define out(y, x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "-----------------------------\n"
#define ENDL(i, n) ((i) == (n)-1 ? "\n" : " ")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
inline void init() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
template <class T> inline istream &operator>>(istream &is, vector<T> &v) {
  for (auto &a : v)
    is >> a;
  return is;
}
template <class T, class U>
inline istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> inline vector<T> vec(size_t a) { return vector<T>(a); }
template <class T> inline vector<T> defvec(T def, size_t a) {
  return vector<T>(a, def);
}
template <class T, class... Ts> inline auto vec(size_t a, Ts... ts) {
  return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...));
}
template <class T, class... Ts> inline auto defvec(T def, size_t a, Ts... ts) {
  return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...));
}
inline void print() { cout << "\n"; }
template <class T, class... Ts> inline void print(const T &a, const Ts &...ts) {
  cout << a << " ";
  print(ts...);
}
template <class T> inline void print(const vector<T> &v) {
  for (int i = 0; i < v.size(); ++i)
    cout << v[i] << (i == v.size() - 1 ? "\n" : " ");
}
template <class T> inline void print(const vector<vector<T>> &v) {
  for (auto &a : v)
    print(a);
}

int main() {
  init();

  int n, k;
  cin >> n >> k;
  k = min(k - 1, n);
  string s;
  cin >> s;
  string u = s;
  reverse(all(u));
  u = s + u;

  char p = *min_element(all(s));
  eFOR(i, 1, n) {
    string t = u.substr(i, n);
    if (0 < k) {
      FOR(c, 0, k - 1) {
        string y = t;
        reverse(all(y));
        t += y;
        int idx = -1, cnt = 0, cur_idx = 0, cur_cnt = 0;
        rFOR(j, 0, n * 2) {
          if (t[j] == p) {
            if (cur_cnt == 0)
              cur_idx = j;
            ++cur_cnt;
          } else {
            if (chmax(cnt, cur_cnt))
              idx = cur_idx;
            cur_cnt = 0;
          }
        }
        if (chmax(cnt, cur_cnt))
          idx = cur_idx;
        t = t.substr(idx - n + 1, n);
      }
      {
        string y = t;
        reverse(all(y));
        t += y;
        int idx = -1, cnt = 0, cur_idx = 0, cur_cnt = 0;
        FOR(j, 0, n * 2) {
          if (t[j] == p) {
            if (cur_cnt == 0)
              cur_idx = j;
            ++cur_cnt;
          } else {
            if (chmax(cnt, cur_cnt))
              idx = cur_idx;
            cur_cnt = 0;
          }
        }
        if (chmax(cnt, cur_cnt))
          idx = cur_idx;
        t = t.substr(idx, n);
      }
    }
    chmin(s, t);
  }
  print(s);
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template <class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, n) for (int(i) = (a); (i) < (n); ++(i))
#define eFOR(i, a, n) for (int(i) = (a); (i) <= (n); ++(i))
#define rFOR(i, a, n) for (int(i) = (n)-1; (i) >= (a); --(i))
#define erFOR(i, a, n) for (int(i) = (n); (i) >= (a); --(i))
#define each(i, a) for (auto &i : a)
#define SORT(i) sort((i).begin(), (i).end())
#define rSORT(i, a) sort((i).begin(), (i).end(), (a))
#define all(i) (i).begin(), (i).end()
#define out(y, x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "-----------------------------\n"
#define ENDL(i, n) ((i) == (n)-1 ? "\n" : " ")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
inline void init() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
template <class T> inline istream &operator>>(istream &is, vector<T> &v) {
  for (auto &a : v)
    is >> a;
  return is;
}
template <class T, class U>
inline istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <class T> inline vector<T> vec(size_t a) { return vector<T>(a); }
template <class T> inline vector<T> defvec(T def, size_t a) {
  return vector<T>(a, def);
}
template <class T, class... Ts> inline auto vec(size_t a, Ts... ts) {
  return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...));
}
template <class T, class... Ts> inline auto defvec(T def, size_t a, Ts... ts) {
  return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...));
}
inline void print() { cout << "\n"; }
template <class T, class... Ts> inline void print(const T &a, const Ts &...ts) {
  cout << a << " ";
  print(ts...);
}
template <class T> inline void print(const vector<T> &v) {
  for (int i = 0; i < v.size(); ++i)
    cout << v[i] << (i == v.size() - 1 ? "\n" : " ");
}
template <class T> inline void print(const vector<vector<T>> &v) {
  for (auto &a : v)
    print(a);
}

int main() {
  init();

  int n, k;
  cin >> n >> k;
  k = min(k - 1, n);
  string s;
  cin >> s;
  string u = s;
  reverse(all(u));
  u = s + u;

  char p = *min_element(all(s));
  eFOR(i, 1, n) {
    string t = u.substr(i, n);
    if (0 < k) {
      FOR(c, 0, k - 1) {
        string y = t;
        reverse(all(y));
        t += y;
        int idx = -1, cnt = 0, cur_idx = 0, cur_cnt = 0;
        rFOR(j, 0, n * 2) {
          if (t[j] == p) {
            if (cur_cnt == 0)
              cur_idx = j;
            ++cur_cnt;
          } else {
            if (chmax(cnt, cur_cnt))
              idx = cur_idx;
            cur_cnt = 0;
          }
        }
        if (chmax(cnt, cur_cnt))
          idx = cur_idx;
        t = t.substr(idx - n + 1, n);
        if (cnt >= n)
          break;
      }
      {
        string y = t;
        reverse(all(y));
        t += y;
        int idx = -1, cnt = 0, cur_idx = 0, cur_cnt = 0;
        FOR(j, 0, n * 2) {
          if (t[j] == p) {
            if (cur_cnt == 0)
              cur_idx = j;
            ++cur_cnt;
          } else {
            if (chmax(cnt, cur_cnt))
              idx = cur_idx;
            cur_cnt = 0;
          }
        }
        if (chmax(cnt, cur_cnt))
          idx = cur_idx;
        t = t.substr(idx, n);
      }
    }
    chmin(s, t);
  }
  print(s);
}