Problem p03987 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC optimize("O3")
#pragma GCC target("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define debug(v)                                                               \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    cout << (v) << endl;                                                       \
  }
#define debugv(v)                                                              \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    for (auto e : (v)) {                                                       \
      cout << e << " ";                                                        \
    }                                                                          \
    cout << endl;                                                              \
  }
#define debuga(m, w)                                                           \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #m);                                         \
    for (int x = 0; x < (w); x++) {                                            \
      cout << (m)[x] << " ";                                                   \
    }                                                                          \
    cout << endl;                                                              \
  }
#define debugaa(m, h, w)                                                       \
  {                                                                            \
    printf("L%d %s >\n", __LINE__, #m);                                        \
    for (int y = 0; y < (h); y++) {                                            \
      for (int x = 0; x < (w); x++) {                                          \
        cout << (m)[y][x] << " ";                                              \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  }
#define ALL(v) (v).begin(), (v).end()
#define repeat(cnt, l) for (auto cnt = 0ll; (cnt) < (l); ++(cnt))
#define rrepeat(cnt, l) for (auto cnt = (l)-1; 0 <= (cnt); --(cnt))
#define iterate(cnt, b, e) for (auto cnt = (b); (cnt) != (e); ++(cnt))
#define diterate(cnt, b, e) for (auto cnt = (b); (cnt) != (e); --(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> p) {
  o << "(" << p.first << ":" << p.second << ")";
  return o;
}
template <typename T> T &maxset(T &to, const T &val) {
  return to = max(to, val);
}
template <typename T> T &minset(T &to, const T &val) {
  return to = min(to, val);
}
void bye(string s, int code = 0) {
  cout << s << endl;
  exit(code);
}
mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
  return uniform_int_distribution<ll>(l, h)(randdev);
}

#if defined(_WIN32) || defined(_WIN64)
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#elif defined(__GNUC__)
#else
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
namespace {
#define isvisiblechar(c) (0x21 <= (c) && (c) <= 0x7E)
class MaiScanner {
public:
  template <typename T> void input_integer(T &var) {
    var = 0;
    T sign = 1;
    int cc = getchar_unlocked();
    for (; cc < '0' || '9' < cc; cc = getchar_unlocked())
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getchar_unlocked())
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
  }
  inline int c() { return getchar_unlocked(); }
  inline MaiScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  inline MaiScanner &operator>>(long long &var) {
    input_integer<long long>(var);
    return *this;
  }
  inline MaiScanner &operator>>(string &var) {
    int cc = getchar_unlocked();
    for (; !isvisiblechar(cc); cc = getchar_unlocked())
      ;
    for (; isvisiblechar(cc); cc = getchar_unlocked())
      var.push_back(cc);
    return *this;
  }
  template <typename IT> void in(IT begin, IT end) {
    for (auto it = begin; it != end; ++it)
      *this >> *it;
  }
};
class MaiPrinter {
public:
  template <typename T> void output_integer(T var) {
    if (var == 0) {
      putchar_unlocked('0');
      return;
    }
    if (var < 0)
      putchar_unlocked('-'), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putchar_unlocked(stack[--stack_p]);
  }
  inline MaiPrinter &operator<<(char c) {
    putchar_unlocked(c);
    return *this;
  }
  inline MaiPrinter &operator<<(int var) {
    output_integer<int>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(long long var) {
    output_integer<long long>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MaiPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar_unlocked(*p++);
    return *this;
  }
  template <typename IT> void join(IT begin, IT end, char sep = '\n') {
    for (auto it = begin; it != end; ++it)
      *this << *it << sep;
  }
};
} // namespace
MaiScanner scanner;
MaiPrinter printer;

typedef ll bsearch_t;
bsearch_t bin_search(bsearch_t low, bsearch_t high,
                     function<bool(bsearch_t)> func) {
  --low;
  bsearch_t c;
  while (low + 1 < high) {
    c = (low + high) / 2;
    (func(c) ? high : low) = c;
  }
  return high;
}

template <typename T = ll> class Bitree {
public:
  int size_;
  vector<T> data_;
  Bitree(int size_) : size_(size_ + 1), data_(size_ + 1) {}

  // 1..rの範囲の値の和を求める．
  T sum(int r) {
    T s = 0;
    while (r) {
      s += data_[r];
      r -= r & -r; //  r&-r と書くことで最下のビットを得る
    }
    return s;
  }
  // l..rの範囲の値の和を求める
  inline T sum(int l, int r) { return sum(r) - sum(l - 1); }
  // idxの要素の値をval増やす
  void add(int idx, T val) {
    while (idx <= size_) {
      data_[idx] += val;
      idx += idx & -idx;
    }
  }
};

ll m, n, kei;

int aa[200010], bb[200010];

int main() {
  scanner >> n;
  repeat(i, n) {
    int a;
    scanner >> a;
    aa[i + 1] = a;
    bb[a] = i + 1;
  }

  Bitree<int> bit(n + 2);
  bit.add(n + 2, 1);

  ll ans = 0;

  iterate(x, 1, n + 1) {
    int i = bb[x];
    int left = 1, right = 1;
    // left
    if (1 < i) {
      ll s = bit.sum(2, i + 1);
      int j =
          bin_search(1, i + 1, [&](int t) { return bit.sum(1, t) == s; }) - 1;
      ++j;
      left = i - j + 1;
    }
    // right
    if (i < n) {
      int j =
          bin_search(i, n + 2, [&](int t) { return bit.sum(i + 1, t) != 0; }) -
          1;
      --j;
      right = j - i + 1;
    }
    ans += ll(left) * ll(right) * ll(x);
    bit.add(i + 1, 1);
  }

  cout << ans << endl;

  return 0;
}

Fixed submission:
#pragma GCC optimize("O3")
#pragma GCC target("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define debug(v)                                                               \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    cout << (v) << endl;                                                       \
  }
#define debugv(v)                                                              \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    for (auto e : (v)) {                                                       \
      cout << e << " ";                                                        \
    }                                                                          \
    cout << endl;                                                              \
  }
#define debuga(m, w)                                                           \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #m);                                         \
    for (int x = 0; x < (w); x++) {                                            \
      cout << (m)[x] << " ";                                                   \
    }                                                                          \
    cout << endl;                                                              \
  }
#define debugaa(m, h, w)                                                       \
  {                                                                            \
    printf("L%d %s >\n", __LINE__, #m);                                        \
    for (int y = 0; y < (h); y++) {                                            \
      for (int x = 0; x < (w); x++) {                                          \
        cout << (m)[y][x] << " ";                                              \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  }
#define ALL(v) (v).begin(), (v).end()
#define repeat(cnt, l) for (auto cnt = 0ll; (cnt) < (l); ++(cnt))
#define rrepeat(cnt, l) for (auto cnt = (l)-1; 0 <= (cnt); --(cnt))
#define iterate(cnt, b, e) for (auto cnt = (b); (cnt) != (e); ++(cnt))
#define diterate(cnt, b, e) for (auto cnt = (b); (cnt) != (e); --(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
template <typename T1, typename T2>
ostream &operator<<(ostream &o, const pair<T1, T2> p) {
  o << "(" << p.first << ":" << p.second << ")";
  return o;
}
template <typename T> T &maxset(T &to, const T &val) {
  return to = max(to, val);
}
template <typename T> T &minset(T &to, const T &val) {
  return to = min(to, val);
}
void bye(string s, int code = 0) {
  cout << s << endl;
  exit(code);
}
mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
  return uniform_int_distribution<ll>(l, h)(randdev);
}

#if defined(_WIN32) || defined(_WIN64)
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#elif defined(__GNUC__)
#else
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
namespace {
#define isvisiblechar(c) (0x21 <= (c) && (c) <= 0x7E)
class MaiScanner {
public:
  template <typename T> void input_integer(T &var) {
    var = 0;
    T sign = 1;
    int cc = getchar_unlocked();
    for (; cc < '0' || '9' < cc; cc = getchar_unlocked())
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getchar_unlocked())
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
  }
  inline int c() { return getchar_unlocked(); }
  inline MaiScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  inline MaiScanner &operator>>(long long &var) {
    input_integer<long long>(var);
    return *this;
  }
  inline MaiScanner &operator>>(string &var) {
    int cc = getchar_unlocked();
    for (; !isvisiblechar(cc); cc = getchar_unlocked())
      ;
    for (; isvisiblechar(cc); cc = getchar_unlocked())
      var.push_back(cc);
    return *this;
  }
  template <typename IT> void in(IT begin, IT end) {
    for (auto it = begin; it != end; ++it)
      *this >> *it;
  }
};
class MaiPrinter {
public:
  template <typename T> void output_integer(T var) {
    if (var == 0) {
      putchar_unlocked('0');
      return;
    }
    if (var < 0)
      putchar_unlocked('-'), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putchar_unlocked(stack[--stack_p]);
  }
  inline MaiPrinter &operator<<(char c) {
    putchar_unlocked(c);
    return *this;
  }
  inline MaiPrinter &operator<<(int var) {
    output_integer<int>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(long long var) {
    output_integer<long long>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MaiPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar_unlocked(*p++);
    return *this;
  }
  template <typename IT> void join(IT begin, IT end, char sep = '\n') {
    for (auto it = begin; it != end; ++it)
      *this << *it << sep;
  }
};
} // namespace
MaiScanner scanner;
MaiPrinter printer;

typedef ll bsearch_t;
bsearch_t bin_search(bsearch_t low, bsearch_t high,
                     function<bool(bsearch_t)> func) {
  --low;
  bsearch_t c;
  while (low + 1 < high) {
    c = (low + high) / 2;
    (func(c) ? high : low) = c;
  }
  return high;
}

template <typename T = ll> class Bitree {
public:
  int size_;
  vector<T> data_;
  Bitree(int size_) : size_(size_ + 1), data_(size_ + 1) {}

  // 1..rの範囲の値の和を求める．
  T sum(int r) {
    T s = 0;
    while (r) {
      s += data_[r];
      r -= r & -r; //  r&-r と書くことで最下のビットを得る
    }
    return s;
  }
  // l..rの範囲の値の和を求める
  inline T sum(int l, int r) { return sum(r) - sum(l - 1); }
  // idxの要素の値をval増やす
  void add(int idx, T val) {
    while (idx <= size_) {
      data_[idx] += val;
      idx += idx & -idx;
    }
  }
};

ll m, n, kei;

int aa[200010], bb[200010];

int main() {
  scanner >> n;
  repeat(i, n) {
    int a;
    scanner >> a;
    aa[i + 1] = a;
    bb[a] = i + 1;
  }

  Bitree<int> bit(n + 5);
  bit.add(n + 2, 1);

  ll ans = 0;

  iterate(x, 1, n + 1) {
    int i = bb[x];
    int left = 1, right = 1;
    // left
    if (1 < i) {
      ll s = bit.sum(2, i + 1);
      int j =
          bin_search(1, i + 1, [&](int t) { return bit.sum(1, t) == s; }) - 1;
      ++j;
      left = i - j + 1;
    }
    // right
    if (i < n) {
      int j =
          bin_search(i, n + 2, [&](int t) { return bit.sum(i + 1, t) != 0; }) -
          1;
      --j;
      right = j - i + 1;
    }
    ans += ll(left) * ll(right) * ll(x);
    bit.add(i + 1, 1);
  }

  cout << ans << endl;

  return 0;
}