Problem p02714 (C++)

Buggy submission (status: Time Limit Exceeded):
/**
 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏
 *    created : 2020-04-13 12:11:29
 **/

// #pragma GCC target("avx512f,avx512dq,avx512cd,avx512bw,avx512vl")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

using int64 = long long;

template <class T>
using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &vec) {
  os << '{';
  size_t n = vec.size();
  for (size_t i = 0; i < n; ++i) {
    os << vec[i];
    if (i != n - 1)
      os << ',';
  }
  os << '}';
  return os;
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
  return os << '{' << p.first << " " << p.second << '}';
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::map<T, U> &mp) {
  os << '{';
  for (auto it = mp.begin(); it != mp.end(); ++it) {
    os << '{' << it->first << ':' << it->second << '}';
    if (it != --mp.end())
      os << ',';
  }
  os << '}';
  return os;
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::set<T> &st) {
  os << '{';
  for (auto it = st.begin(); it != st.end(); ++it) {
    os << *it;
    if (it != --st.end())
      os << ',';
  }
  os << '}';
  return os;
}
template <class T>
std::istream &operator>>(std::istream &is, std::vector<T> &vec) {
  size_t n = vec.size();
  for (size_t i = 0; i < n; ++i)
    is >> vec[i];
  return is;
}

#define all(_) begin(_), end(_)
#define rall(_) rbegin(_), rend(_)

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() { std::cerr << '\n'; }

template <class Head, class... Tail>
void debug_out(Head &&head, Tail &&...tail) {
  std::cerr << head;
  if (sizeof...(Tail) != 0)
    std::cerr << ", ";
  debug_out(std::forward<Tail>(tail)...);
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  int n;
  cin >> n;
  string s;
  cin >> s;

  int64 ans = 0;

  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      if (s[i] == s[j])
        continue;
      for (int k = j + 1; k < n; ++k) {
        if (s[j] != s[k] && s[i] != s[k] && j - i != k - j)
          ++ans;
      }
    }
  }

  cout << ans << '\n';

  return 0;
}

Fixed submission:
/**
 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏
 *    created : 2020-04-13 12:11:29
 **/

#pragma GCC target("avx512f,avx512dq,avx512cd,avx512bw,avx512vl")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

using int64 = long long;

template <class T>
using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &vec) {
  os << '{';
  size_t n = vec.size();
  for (size_t i = 0; i < n; ++i) {
    os << vec[i];
    if (i != n - 1)
      os << ',';
  }
  os << '}';
  return os;
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
  return os << '{' << p.first << " " << p.second << '}';
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::map<T, U> &mp) {
  os << '{';
  for (auto it = mp.begin(); it != mp.end(); ++it) {
    os << '{' << it->first << ':' << it->second << '}';
    if (it != --mp.end())
      os << ',';
  }
  os << '}';
  return os;
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::set<T> &st) {
  os << '{';
  for (auto it = st.begin(); it != st.end(); ++it) {
    os << *it;
    if (it != --st.end())
      os << ',';
  }
  os << '}';
  return os;
}
template <class T>
std::istream &operator>>(std::istream &is, std::vector<T> &vec) {
  size_t n = vec.size();
  for (size_t i = 0; i < n; ++i)
    is >> vec[i];
  return is;
}

#define all(_) begin(_), end(_)
#define rall(_) rbegin(_), rend(_)

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() { std::cerr << '\n'; }

template <class Head, class... Tail>
void debug_out(Head &&head, Tail &&...tail) {
  std::cerr << head;
  if (sizeof...(Tail) != 0)
    std::cerr << ", ";
  debug_out(std::forward<Tail>(tail)...);
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  int n;
  cin >> n;
  string s;
  cin >> s;

  int64 ans = 0;

  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      if (s[i] == s[j])
        continue;
      for (int k = j + 1; k < n; ++k) {
        if (s[j] != s[k] && s[i] != s[k] && j - i != k - j)
          ++ans;
      }
    }
  }

  cout << ans << '\n';

  return 0;
}