Problem p03050 (C++)

Buggy submission (status: Runtime Error):

#pragma GCC optimize("O3")
#include "bits/stdc++.h"

using namespace std;
using ll = long long int;

#define debugos cout
#define debug(v)                                                               \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    debugos << (v) << endl;                                                    \
  }
#define debugv(v)                                                              \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    for (auto e : (v)) {                                                       \
      debugos << e << " ";                                                     \
    }                                                                          \
    debugos << endl;                                                           \
  }
#define debuga(m, w)                                                           \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #m);                                         \
    for (int x = 0; x < (w); x++) {                                            \
      debugos << (m)[x] << " ";                                                \
    }                                                                          \
    debugos << 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++) {                                          \
        debugos << (m)[y][x] << " ";                                           \
      }                                                                        \
      debugos << endl;                                                         \
    }                                                                          \
  }
#define all(v) (v).begin(), (v).end()
#define repeat(cnt, l) for (auto cnt = decltype(l)(); (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))
const ll MD = 1000000007ll;
const long double PI = 3.1415926535897932384626433832795L;
inline void assert_call(bool assertion, function<void()> f) {
  if (!assertion) {
    cerr << "assertion fault:" << endl;
    f();
    abort();
  }
}
template <typename T1, typename T2>
inline ostream &operator<<(ostream &o, const pair<T1, T2> p) {
  o << '(' << p.first << ':' << p.second << ')';
  return o;
}
template <typename Vec>
inline ostream &_ostream_vecprint(ostream &os, const Vec &a) {
  os << '[';
  for (const auto &e : a)
    os << ' ' << e << ' ';
  os << ']';
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &o, const vector<T> &v) {
  return _ostream_vecprint(o, v);
}
template <typename T, size_t S>
inline ostream &operator<<(ostream &o, const array<T, S> &v) {
  return _ostream_vecprint(o, v);
}
template <typename T> inline T &chmax(T &to, const T &val) {
  return to = max(to, val);
}
template <typename T> inline T &chmin(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);
template <typename T, typename Random = decltype(randdev),
          typename enable_if<is_integral<T>::value>::type * = nullptr>
inline T rand(T l, T h, Random &rand = randdev) {
  return uniform_int_distribution<T>(l, h)(rand);
}
template <typename T, typename Random = decltype(randdev),
          typename enable_if<is_floating_point<T>::value>::type * = nullptr>
inline T rand(T l, T h, Random &rand = randdev) {
  return uniform_real_distribution<T>(l, h)(rand);
}

#if defined(_WIN32) || defined(_WIN64)
#define getc_x _getc_nolock
#define putc_x _putc_nolock
#elif defined(__GNUC__)
#define getc_x getc_unlocked
#define putc_x putc_unlocked
#else
#define getc_x getc
#define putc_x putc
#endif
#define isvisiblechar(c) (0x21 <= (c) && (c) <= 0x7E)
class MaiScanner {
  FILE *fp_;

public:
  inline MaiScanner(FILE *fp) : fp_(fp) {}
  template <typename T> void input_integer(T &var) noexcept {
    var = 0;
    T sign = 1;
    int cc = getc_x(fp_);
    for (; cc < '0' || '9' < cc; cc = getc_x(fp_))
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getc_x(fp_))
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
  }
  inline int c() noexcept { return getc_x(fp_); }
  inline MaiScanner &operator>>(int &var) noexcept {
    input_integer<int>(var);
    return *this;
  }
  inline MaiScanner &operator>>(long long &var) noexcept {
    input_integer<long long>(var);
    return *this;
  }
  inline MaiScanner &operator>>(string &var) {
    int cc = getc_x(fp_);
    for (; !isvisiblechar(cc); cc = getc_x(fp_))
      ;
    for (; isvisiblechar(cc); cc = getc_x(fp_))
      var.push_back(cc);
    return *this;
  }
  template <typename IT> inline void in(IT begin, IT end) {
    for (auto it = begin; it != end; ++it)
      *this >> *it;
  }
};
class MaiPrinter {
  FILE *fp_;

public:
  inline MaiPrinter(FILE *fp) : fp_(fp) {}
  template <typename T> void output_integer(T var) noexcept {
    if (var == 0) {
      putc_x('0', fp_);
      return;
    }
    if (var < 0)
      putc_x('-', fp_), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putc_x(stack[--stack_p], fp_);
  }
  inline MaiPrinter &operator<<(char c) noexcept {
    putc_x(c, fp_);
    return *this;
  }
  inline MaiPrinter &operator<<(int var) noexcept {
    output_integer<int>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(long long var) noexcept {
    output_integer<long long>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(char *str_p) noexcept {
    while (*str_p)
      putc_x(*(str_p++), fp_);
    return *this;
  }
  inline MaiPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putc_x(*p++, fp_);
    return *this;
  }
  template <typename IT> void join(IT begin, IT end, char sep = ' ') {
    for (bool b = 0; begin != end; ++begin, b = 1)
      b ? *this << sep << *begin : *this << *begin;
  }
};
MaiScanner scanner(stdin);
MaiPrinter printer(stdout);

//

ll N;
ll sqN;

// x = n/m
// (n-m) = x*m
ll has(ll x) {
  ll low = 1, high = 1000000ll;
  if (N - x == x)
    return 1;
  if (N - 1000000ll == x * 1000000ll)
    return 1000000ll;

  while (high - low > 1) {
    ll mid = (high + low) / 2;
    ll v = (N - x) - (x * mid);
    if (v == 0)
      return mid;
    else if (v < 0)
      high = mid;
    else
      low = mid;
  }
  return 0;
}

int main() {

  scanner >> N;
  sqN = static_cast<ll>(floor(sqrt(N)));

  ll reiwa = 0;
  iterate(x, 1ll, sqN + 1) {
    // ll t = has(x);
    ll m = (N - x) / x;
    if (N / m == N % m) {
      reiwa += m;
    }
  }

  cout << reiwa << endl;

  return 0;
}


Fixed submission:

#pragma GCC optimize("O3")
#include "bits/stdc++.h"

using namespace std;
using ll = long long int;

#define debugos cout
#define debug(v)                                                               \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    debugos << (v) << endl;                                                    \
  }
#define debugv(v)                                                              \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #v);                                         \
    for (auto e : (v)) {                                                       \
      debugos << e << " ";                                                     \
    }                                                                          \
    debugos << endl;                                                           \
  }
#define debuga(m, w)                                                           \
  {                                                                            \
    printf("L%d %s > ", __LINE__, #m);                                         \
    for (int x = 0; x < (w); x++) {                                            \
      debugos << (m)[x] << " ";                                                \
    }                                                                          \
    debugos << 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++) {                                          \
        debugos << (m)[y][x] << " ";                                           \
      }                                                                        \
      debugos << endl;                                                         \
    }                                                                          \
  }
#define all(v) (v).begin(), (v).end()
#define repeat(cnt, l) for (auto cnt = decltype(l)(); (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))
const ll MD = 1000000007ll;
const long double PI = 3.1415926535897932384626433832795L;
inline void assert_call(bool assertion, function<void()> f) {
  if (!assertion) {
    cerr << "assertion fault:" << endl;
    f();
    abort();
  }
}
template <typename T1, typename T2>
inline ostream &operator<<(ostream &o, const pair<T1, T2> p) {
  o << '(' << p.first << ':' << p.second << ')';
  return o;
}
template <typename Vec>
inline ostream &_ostream_vecprint(ostream &os, const Vec &a) {
  os << '[';
  for (const auto &e : a)
    os << ' ' << e << ' ';
  os << ']';
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &o, const vector<T> &v) {
  return _ostream_vecprint(o, v);
}
template <typename T, size_t S>
inline ostream &operator<<(ostream &o, const array<T, S> &v) {
  return _ostream_vecprint(o, v);
}
template <typename T> inline T &chmax(T &to, const T &val) {
  return to = max(to, val);
}
template <typename T> inline T &chmin(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);
template <typename T, typename Random = decltype(randdev),
          typename enable_if<is_integral<T>::value>::type * = nullptr>
inline T rand(T l, T h, Random &rand = randdev) {
  return uniform_int_distribution<T>(l, h)(rand);
}
template <typename T, typename Random = decltype(randdev),
          typename enable_if<is_floating_point<T>::value>::type * = nullptr>
inline T rand(T l, T h, Random &rand = randdev) {
  return uniform_real_distribution<T>(l, h)(rand);
}

#if defined(_WIN32) || defined(_WIN64)
#define getc_x _getc_nolock
#define putc_x _putc_nolock
#elif defined(__GNUC__)
#define getc_x getc_unlocked
#define putc_x putc_unlocked
#else
#define getc_x getc
#define putc_x putc
#endif
#define isvisiblechar(c) (0x21 <= (c) && (c) <= 0x7E)
class MaiScanner {
  FILE *fp_;

public:
  inline MaiScanner(FILE *fp) : fp_(fp) {}
  template <typename T> void input_integer(T &var) noexcept {
    var = 0;
    T sign = 1;
    int cc = getc_x(fp_);
    for (; cc < '0' || '9' < cc; cc = getc_x(fp_))
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getc_x(fp_))
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
  }
  inline int c() noexcept { return getc_x(fp_); }
  inline MaiScanner &operator>>(int &var) noexcept {
    input_integer<int>(var);
    return *this;
  }
  inline MaiScanner &operator>>(long long &var) noexcept {
    input_integer<long long>(var);
    return *this;
  }
  inline MaiScanner &operator>>(string &var) {
    int cc = getc_x(fp_);
    for (; !isvisiblechar(cc); cc = getc_x(fp_))
      ;
    for (; isvisiblechar(cc); cc = getc_x(fp_))
      var.push_back(cc);
    return *this;
  }
  template <typename IT> inline void in(IT begin, IT end) {
    for (auto it = begin; it != end; ++it)
      *this >> *it;
  }
};
class MaiPrinter {
  FILE *fp_;

public:
  inline MaiPrinter(FILE *fp) : fp_(fp) {}
  template <typename T> void output_integer(T var) noexcept {
    if (var == 0) {
      putc_x('0', fp_);
      return;
    }
    if (var < 0)
      putc_x('-', fp_), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putc_x(stack[--stack_p], fp_);
  }
  inline MaiPrinter &operator<<(char c) noexcept {
    putc_x(c, fp_);
    return *this;
  }
  inline MaiPrinter &operator<<(int var) noexcept {
    output_integer<int>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(long long var) noexcept {
    output_integer<long long>(var);
    return *this;
  }
  inline MaiPrinter &operator<<(char *str_p) noexcept {
    while (*str_p)
      putc_x(*(str_p++), fp_);
    return *this;
  }
  inline MaiPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putc_x(*p++, fp_);
    return *this;
  }
  template <typename IT> void join(IT begin, IT end, char sep = ' ') {
    for (bool b = 0; begin != end; ++begin, b = 1)
      b ? *this << sep << *begin : *this << *begin;
  }
};
MaiScanner scanner(stdin);
MaiPrinter printer(stdout);

//

ll N;
ll sqN;

// x = n/m
// (n-m) = x*m
ll has(ll x) {
  ll low = 1, high = 1000000ll;
  if (N - x == x)
    return 1;
  if (N - 1000000ll == x * 1000000ll)
    return 1000000ll;

  while (high - low > 1) {
    ll mid = (high + low) / 2;
    ll v = (N - x) - (x * mid);
    if (v == 0)
      return mid;
    else if (v < 0)
      high = mid;
    else
      low = mid;
  }
  return 0;
}

int main() {

  scanner >> N;
  if (N <= 2)
    bye("0");
  sqN = static_cast<ll>(floor(sqrt(N)));

  ll reiwa = 0;
  iterate(x, 1ll, sqN + 1) {
    // ll t = has(x);
    ll m = (N - x) / x;
    if (N / m == N % m) {
      reiwa += m;
    }
  }

  cout << reiwa << endl;

  return 0;
}