Problem p03201 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;

long long int INF = 1e18;
long long int mod = 1000000007;
double Pi = 3.1415926535897932384626;

vector<ll> G[500005];
vector<P> tree[500010];
priority_queue<ll> pql;
priority_queue<P> pqp;
// big priority queue
priority_queue<ll, vector<ll>, greater<ll>> pqls;
priority_queue<P, vector<P>, greater<P>> pqps;
// small priority queue
// top pop

int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
int dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
char dir[] = "RULD";
// ↓,→,↑,←

#define p(x) cout << x << endl;
#define el cout << endl;
#define pe(x) cout << x << " ";
#define ps(x) cout << fixed << setprecision(25) << x << endl;
#define pu(x) cout << x;
#define re(i, n)                                                               \
  for (i = 0; i < n; i++)                                                      \
    ;
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define deba(x) cout << #x << " = " << x << endl

ll rui(ll number1, ll number2) {
  if (number2 == 0) {
    return 1;
  } else {
    ll number3 = rui(number1, number2 / 2);
    number3 *= number3;
    number3 %= mod;
    if (number2 % 2 == 1) {
      number3 *= number1;
      number3 %= mod;
    }
    return number3;
  }
}
ll gcd(ll number1, ll number2) {
  if (number1 > number2) {
    swap(number1, number2);
  }
  if (number1 == 0 || number1 == number2) {
    return number2;
  } else {
    return gcd(number2 % number1, number1);
  }
}

ll i, j, k, ii, jj;
ll n, m;
ll a, b, c, d, e, g, h, r;
ll l, ans, num;
ll x[500005], y[500005], z[500005];
bool dame, flag;
char s[500005], t[500005];
bool used[500005];

int main() {
  cin >> n;
  map<ll, ll> kazu;
  for (i = 0; i < n; i++) {
    cin >> x[i];
    kazu[x[i]]++;
  }
  sort(x, x + n);
  reverse(x, x + n);
  for (i = 0; i < n; i++) {
    // pe(x[i]);p(kazu[x[i]]);
    if (kazu[x[i]] <= 0)
      continue;
    for (j = 32; j >= 0; j--) {
      num = (1ll << j);
      // p(num);
      // if(num < x[i])break;
      if (num == x[i] * 2) {
        if (kazu[x[i]] >= 2) {
          kazu[x[i]] -= 2;
          ans++;
          break;
        }
      } else {
        if (kazu[num - x[i]] >= 1) {
          kazu[x[i]]--;
          kazu[num - x[i]]--;
          ans++;
          break;
        }
      }
    }
  }

  p(ans);
  return 0;
}

Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;

long long int INF = 1e18;
long long int mod = 1000000007;
double Pi = 3.1415926535897932384626;

vector<ll> G[500005];
vector<P> tree[500010];
priority_queue<ll> pql;
priority_queue<P> pqp;
// big priority queue
priority_queue<ll, vector<ll>, greater<ll>> pqls;
priority_queue<P, vector<P>, greater<P>> pqps;
// small priority queue
// top pop

int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
int dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
char dir[] = "RULD";
// ↓,→,↑,←

#define p(x) cout << x << endl;
#define el cout << endl;
#define pe(x) cout << x << " ";
#define ps(x) cout << fixed << setprecision(25) << x << endl;
#define pu(x) cout << x;
#define re(i, n)                                                               \
  for (i = 0; i < n; i++)                                                      \
    ;
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define deba(x) cout << #x << " = " << x << endl

ll rui(ll number1, ll number2) {
  if (number2 == 0) {
    return 1;
  } else {
    ll number3 = rui(number1, number2 / 2);
    number3 *= number3;
    number3 %= mod;
    if (number2 % 2 == 1) {
      number3 *= number1;
      number3 %= mod;
    }
    return number3;
  }
}
ll gcd(ll number1, ll number2) {
  if (number1 > number2) {
    swap(number1, number2);
  }
  if (number1 == 0 || number1 == number2) {
    return number2;
  } else {
    return gcd(number2 % number1, number1);
  }
}

ll i, j, k, ii, jj;
ll n, m;
ll a, b, c, d, e, g, h, r;
ll l, ans, num;
ll x[500005], y[500005], z[500005];
bool dame, flag;
char s[500005], t[500005];
bool used[500005];

int main() {
  cin >> n;
  map<ll, ll> kazu;
  for (i = 0; i < n; i++) {
    cin >> x[i];
    kazu[x[i]]++;
  }
  sort(x, x + n);
  reverse(x, x + n);
  for (i = 0; i < n; i++) {
    // pe(x[i]);p(kazu[x[i]]);
    if (kazu[x[i]] <= 0)
      continue;
    for (j = 32; j >= 0; j--) {
      num = (1ll << j);
      // p(num);
      if (num < x[i])
        break;
      if (num == x[i] * 2) {
        if (kazu[x[i]] >= 2) {
          kazu[x[i]] -= 2;
          ans++;
          break;
        }
      } else {
        if (kazu[num - x[i]] >= 1) {
          kazu[x[i]]--;
          kazu[num - x[i]]--;
          ans++;
          break;
        }
      }
    }
  }

  p(ans);
  return 0;
}