Problem p03201 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)

using ll = long long;
using ld = long double;
ll INF = LLONG_MAX;

using vi = vector<int>;
using vll = vector<ll>;
using pii = pair<int, int>;

namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(ld x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char *x) { cout << x; }
void pr(const string &x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template <class T> void pr(const complex<T> &x) { cout << x; }

template <class T1, class T2> void pr(const pair<T1, T2> &x);
template <class T> void pr(const T &x);

template <class T, class... Ts> void pr(const T &t, const Ts &...ts) {
  pr(t);
  pr(ts...);
}
template <class T1, class T2> void pr(const pair<T1, T2> &x) {
  pr("{", x.f, ", ", x.s, "}");
}
template <class T> void pr(const T &x) {
  pr("{"); // const iterator needed for vector<bool>
  bool fst = 1;
  for (const auto &a : x)
    pr(!fst ? ", " : "", a), fst = 0;
  pr("}");
}

void print() { pr("\n"); } // print w/ spaces
template <class T, class... Ts> void print(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(" ");
  print(ts...);
}
} // namespace output

using namespace output;

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int N;
  cin >> N;
  vi arr(N);
  F0R(i, N) cin >> arr[i];
  sort(arr.begin(), arr.end());
  reverse(arr.begin(), arr.end());
  int matches = 0;
  for (int i = 0; i < arr.size(); ++i) {
    int val = arr[i];
    int pow = 1 << ((int)log2(val) + 1);

    int l = i + 1;
    int r = arr.size() - 1;
    while (l < r) {
      int mid = l + (r - l) / 2;
      if (arr[mid] > pow - val) {
        l = mid + 1;
      } else {
        r = mid;
      }
    }

    if (l < N && arr[l] == pow - val) {
      arr.erase(arr.begin() + l);
      ++matches;
    }
  }
  print(matches);
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)

using ll = long long;
using ld = long double;
ll INF = LLONG_MAX;

using vi = vector<int>;
using vll = vector<ll>;
using pii = pair<int, int>;

namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(ld x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char *x) { cout << x; }
void pr(const string &x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template <class T> void pr(const complex<T> &x) { cout << x; }

template <class T1, class T2> void pr(const pair<T1, T2> &x);
template <class T> void pr(const T &x);

template <class T, class... Ts> void pr(const T &t, const Ts &...ts) {
  pr(t);
  pr(ts...);
}
template <class T1, class T2> void pr(const pair<T1, T2> &x) {
  pr("{", x.f, ", ", x.s, "}");
}
template <class T> void pr(const T &x) {
  pr("{"); // const iterator needed for vector<bool>
  bool fst = 1;
  for (const auto &a : x)
    pr(!fst ? ", " : "", a), fst = 0;
  pr("}");
}

void print() { pr("\n"); } // print w/ spaces
template <class T, class... Ts> void print(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(" ");
  print(ts...);
}
} // namespace output

using namespace output;

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int N;
  cin >> N;
  vi arr(N);
  F0R(i, N) cin >> arr[i];
  sort(arr.begin(), arr.end());
  reverse(arr.begin(), arr.end());
  int matches = 0;
  for (int i = 0; i < arr.size(); ++i) {
    int val = arr[i];
    int pow = 1 << ((int)log2(val) + 1);

    int l = i + 1;
    int r = arr.size() - 1;
    while (l < r) {
      int mid = l + (r - l) / 2;
      if (arr[mid] > pow - val) {
        l = mid + 1;
      } else {
        r = mid;
      }
    }

    if (l < arr.size() && arr[l] == pow - val) {
      arr.erase(arr.begin() + l);
      ++matches;
    }
  }
  print(matches);
}