Problem p03201 (C++)

Buggy submission (status: Time Limit Exceeded):
#include "bits/stdc++.h"

using namespace std;
#ifdef _DEBUG
#define _GLIBCXX_DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define ll long long
#define ll1 1ll
#define ONE 1ll
#define DBG 1
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define loop(n) rep(loop, (0), (n))
#define all(c) begin(c), end(c)
const int INF =
    sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
const double PI = acos(-1);
const double EPS = 1e-9;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
using pii = pair<int, int>;
// template<class T> ostream &operator<<(ostream &os,T &t){dump(t);return os;}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> &p) {
  os << p.first << " " << p.second;
  return os;
}

template <typename T> void printvv(const vector<vector<T>> &v) {
  cerr << endl;
  rep(i, 0, v.size()) rep(j, 0, v[i].size()) {
    if (typeid(v[i][j]).name() == typeid(INF).name() and v[i][j] == INF) {
      cerr << "INF";
    } else
      cerr << v[i][j];
    cerr << (j == v[i].size() - 1 ? '\n' : ' ');
  }
  cerr << endl;
}
/*
typedef __int128_t Int;
std::ostream &operator<<(std::ostream &dest, __int128_t value) {
std::ostream::sentry s(dest);
  if (s) {
        __uint128_t tmp = value < 0 ? -value : value;
        char buffer[128];
        char *d = std::end(buffer);
        do {
          --d;
          *d = "0123456789"[tmp % 10];
          tmp /= 10;
        } while (tmp != 0);
        if (value < 0) {
          --d;
          *d = '-';
        }
        int len = std::end(buffer) - d;
        if (dest.rdbuf()->sputn(d, len) != len) {
          dest.setstate(std::ios_base::badbit);
        }
  }
  return dest;
}

__int128 parse(string &s) {
  __int128 ret = 0;
  for (int i = 0; i < s.length(); i++)
        if ('0' <= s[i] && s[i] <= '9')
          ret = 10 * ret + s[i] - '0';
  return ret;
}
*/

#ifndef _DEBUG
#define printvv(...)
#endif
void YES(bool f) { cout << (f ? "YES" : "NO") << endl; }
void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; }
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

signed main(signed argc, char *argv[]) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);

  int N;
  cin >> N;
  vector<int> A(N);
  rep(i, 0, N) { cin >> A[i]; }
  int ans = 0;
  map<int, int> mp;
  rep(i, 0, N) mp[A[i]]++;
  sort(all(A), greater<int>());
  rep(i, 0, N) {
    if (mp[A[i]]) {
      mp[A[i]]--;
      rep(j, 0, 35) {
        int x = (1ll << j) - A[i];
        if (mp[x]) {
          mp[x]--;
          ans++;
        }
      }
    }
  }
  dump(mp.size());
  cout << ans << endl;

  return 0;
}


Fixed submission:
#include "bits/stdc++.h"

using namespace std;
#ifdef _DEBUG
#define _GLIBCXX_DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define ll long long
#define ll1 1ll
#define ONE 1ll
#define DBG 1
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define loop(n) rep(loop, (0), (n))
#define all(c) begin(c), end(c)
const int INF =
    sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
const double PI = acos(-1);
const double EPS = 1e-9;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
using pii = pair<int, int>;
// template<class T> ostream &operator<<(ostream &os,T &t){dump(t);return os;}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> &p) {
  os << p.first << " " << p.second;
  return os;
}

template <typename T> void printvv(const vector<vector<T>> &v) {
  cerr << endl;
  rep(i, 0, v.size()) rep(j, 0, v[i].size()) {
    if (typeid(v[i][j]).name() == typeid(INF).name() and v[i][j] == INF) {
      cerr << "INF";
    } else
      cerr << v[i][j];
    cerr << (j == v[i].size() - 1 ? '\n' : ' ');
  }
  cerr << endl;
}
/*
typedef __int128_t Int;
std::ostream &operator<<(std::ostream &dest, __int128_t value) {
std::ostream::sentry s(dest);
  if (s) {
        __uint128_t tmp = value < 0 ? -value : value;
        char buffer[128];
        char *d = std::end(buffer);
        do {
          --d;
          *d = "0123456789"[tmp % 10];
          tmp /= 10;
        } while (tmp != 0);
        if (value < 0) {
          --d;
          *d = '-';
        }
        int len = std::end(buffer) - d;
        if (dest.rdbuf()->sputn(d, len) != len) {
          dest.setstate(std::ios_base::badbit);
        }
  }
  return dest;
}

__int128 parse(string &s) {
  __int128 ret = 0;
  for (int i = 0; i < s.length(); i++)
        if ('0' <= s[i] && s[i] <= '9')
          ret = 10 * ret + s[i] - '0';
  return ret;
}
*/

#ifndef _DEBUG
#define printvv(...)
#endif
void YES(bool f) { cout << (f ? "YES" : "NO") << endl; }
void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; }
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

signed main(signed argc, char *argv[]) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(12);

  int N;
  cin >> N;
  vector<int> A(N);
  rep(i, 0, N) { cin >> A[i]; }
  int ans = 0;
  map<int, int> mp;
  rep(i, 0, N) mp[A[i]]++;
  sort(all(A), greater<int>());
  rep(i, 0, N) {
    if (mp[A[i]]) {
      mp[A[i]]--;
      rep(j, 0, 35) {
        int x = (1ll << j) - A[i];
        if (mp.count(x) and mp[x]) {
          mp[x]--;
          ans++;
        }
      }
    }
  }
  dump(mp.size());
  cout << ans << endl;

  return 0;
}