Problem p00469 (C++) — buggy submission, verdict: Time Limit Exceeded

#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#include <random>

using namespace std;

// 呪文
#define DUMPOUT cerr
#define dump(...)                                                              \\
  DUMPOUT << "  ";                                                             \\
  DUMPOUT << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]"   \\
          << endl;                                                             \\
  DUMPOUT << "    ";                                                           \\
  dump_func(__VA_ARGS__)

typedef unsigned uint;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
typedef pair<string, string> pss;
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &ostr, const pair<_KTy, _Ty> &m) {
  ostr << "{" << m.first << ", " << m.second << "}";
  return ostr;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &ostr, const map<_KTy, _Ty> &m) {
  if (m.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty>
ostream &operator<<(ostream &ostr, const vector<_Ty> &v) {
  if (v.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty> ostream &operator<<(ostream &ostr, const set<_Ty> &s) {
  if (s.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty>
ostream &operator<<(ostream &ostr, const stack<_Ty> &s) {
  if (s.empty()) {
    ostr << "{ }";
    return ostr;
  }
  stack<_Ty> t(s);
  ostr << "{" << t.top();
  t.pop();
  while (!t.empty()) {
    ostr << ", " << t.top();
    t.pop();
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty> ostream &operator<<(ostream &ostr, const list<_Ty> &l) {
  if (l.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << l.front();
  for (auto itr = ++l.begin(); itr != l.end(); ++itr) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _KTy, typename _Ty>
istream &operator>>(istream &istr, pair<_KTy, _Ty> &m) {
  istr >> m.first >> m.second;
  return istr;
}
template <typename _Ty> istream &operator>>(istream &istr, vector<_Ty> &v) {
  for (size_t i = 0; i < v.size(); i++)
    istr >> v[i];
  return istr;
}
namespace aux { // print tuple
template <typename Ty, unsigned N, unsigned L> struct tp {
  static void print(ostream &os, const Ty &v) {
    os << get<N>(v) << ", ";
    tp<Ty, N + 1, L>::print(os, v);
  }
};
template <typename Ty, unsigned N> struct tp<Ty, N, N> {
  static void print(ostream &os, const Ty &value) { os << get<N>(value); }
};
} // namespace aux
template <typename... Tys>
ostream &operator<<(ostream &os, const tuple<Tys...> &t) {
  os << "{";
  aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t);
  os << "}";
  return os;
}

template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&...tail) {
  DUMPOUT << head;
  if (sizeof...(Tail) == 0) {
    DUMPOUT << " ";
  } else {
    DUMPOUT << ", ";
  }
  dump_func(std::move(tail)...);
}

#define PI 3.14159265358979323846
#define EPS 1e-11
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define fake false

// サイズ k の部分集合の列挙 a
template <typename Ty> Ty next_combination_bit(Ty n, Ty k) {
  Ty cnt = 0;
  Ty c = (1 << k) - 1;
  while (c < 1 << n) {
    cnt++;
    Ty x = c & -c, y = c + x;
    c = ((c & ~y) / x >> 1) | y;
  }
  return cnt;
}

int main() {
  // clock_t start, end;
  // start = clock();

  cin.tie(0);
  ios::sync_with_stdio(false);

  while (true) {
    int n, k;
    cin >> n >> k;
    if (n == 0 && k == 0)
      break;

    vector<int> v(n);
    cin >> v;

    sort(all(v));

    set<string> st;

    int c = (1 << k) - 1;
    while (c < 1 << n) {

      vector<int> vv;
      for (int b = 0; b < n; b++)
        if ((c >> b) & 1)
          vv.push_back(v[b]);

      sort(all(vv));

      do {
        if (vv[0] == 0)
          continue;

        string s;
        for (int i = 0; i < k; i++)
          s += to_string(vv[i]);
        st.insert(s);

      } while (next_permutation(all(vv)));

      int x = c & -c, y = c + x;
      c = ((c & ~y) / x >> 1) | y;
    }

    cout << st.size() << endl;
  }

  // end = clock();
  // printf("%d msec.\\n", end - start);

  return 0;
}


Error: TLE

Fixed submission:

#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
#include <random>

using namespace std;

// 呪文
#define DUMPOUT cerr
#define dump(...)                                                              \\
  DUMPOUT << "  ";                                                             \\
  DUMPOUT << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]"   \\
          << endl;                                                             \\
  DUMPOUT << "    ";                                                           \\
  dump_func(__VA_ARGS__)

typedef unsigned uint;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
typedef pair<string, string> pss;
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &ostr, const pair<_KTy, _Ty> &m) {
  ostr << "{" << m.first << ", " << m.second << "}";
  return ostr;
}
template <typename _KTy, typename _Ty>
ostream &operator<<(ostream &ostr, const map<_KTy, _Ty> &m) {
  if (m.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << *m.begin();
  for (auto itr = ++m.begin(); itr != m.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty>
ostream &operator<<(ostream &ostr, const vector<_Ty> &v) {
  if (v.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << v.front();
  for (auto itr = ++v.begin(); itr != v.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty> ostream &operator<<(ostream &ostr, const set<_Ty> &s) {
  if (s.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << *(s.begin());
  for (auto itr = ++s.begin(); itr != s.end(); itr++) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty>
ostream &operator<<(ostream &ostr, const stack<_Ty> &s) {
  if (s.empty()) {
    ostr << "{ }";
    return ostr;
  }
  stack<_Ty> t(s);
  ostr << "{" << t.top();
  t.pop();
  while (!t.empty()) {
    ostr << ", " << t.top();
    t.pop();
  }
  ostr << "}";
  return ostr;
}
template <typename _Ty> ostream &operator<<(ostream &ostr, const list<_Ty> &l) {
  if (l.empty()) {
    ostr << "{ }";
    return ostr;
  }
  ostr << "{" << l.front();
  for (auto itr = ++l.begin(); itr != l.end(); ++itr) {
    ostr << ", " << *itr;
  }
  ostr << "}";
  return ostr;
}
template <typename _KTy, typename _Ty>
istream &operator>>(istream &istr, pair<_KTy, _Ty> &m) {
  istr >> m.first >> m.second;
  return istr;
}
template <typename _Ty> istream &operator>>(istream &istr, vector<_Ty> &v) {
  for (size_t i = 0; i < v.size(); i++)
    istr >> v[i];
  return istr;
}
namespace aux { // print tuple
template <typename Ty, unsigned N, unsigned L> struct tp {
  static void print(ostream &os, const Ty &v) {
    os << get<N>(v) << ", ";
    tp<Ty, N + 1, L>::print(os, v);
  }
};
template <typename Ty, unsigned N> struct tp<Ty, N, N> {
  static void print(ostream &os, const Ty &value) { os << get<N>(value); }
};
} // namespace aux
template <typename... Tys>
ostream &operator<<(ostream &os, const tuple<Tys...> &t) {
  os << "{";
  aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t);
  os << "}";
  return os;
}

template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&...tail) {
  DUMPOUT << head;
  if (sizeof...(Tail) == 0) {
    DUMPOUT << " ";
  } else {
    DUMPOUT << ", ";
  }
  dump_func(std::move(tail)...);
}

#define PI 3.14159265358979323846
#define EPS 1e-11
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define fake false

int main() {
  // clock_t start, end;
  // start = clock();

  cin.tie(0);
  ios::sync_with_stdio(false);

  while (true) {
    int n, k;
    cin >> n >> k;
    if (n == 0 && k == 0)
      break;

    vector<int> v(n);
    cin >> v;

    sort(all(v));

    set<string> st;
    do {
      string s;
      if (v[0] == 0)
        continue;
      for (int i = 0; i < k; i++) {
        s += to_string(v[i]);
      }
      st.insert(s);
    } while (next_permutation(all(v)));

    cout << st.size() << endl;
  }

  // end = clock();
  // printf("%d msec.\\n", end - start);

  return 0;
}