Problem p02401 (C++) — buggy submission, verdict: Time Limit Exceeded

#ifdef LOCAL
#pragma GCC optimize("O0")
#else
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>

using namespace std;
using namespace std::placeholders;

using ll = long long;
const int INF = 1e9 + 7;
const ll INF_LL = 1e18 + 7;

#define __overload3(_1, _2, _3, name, ...) name
#define rep(...)                                                               \\
  __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until)                                        \\
  for (int name = from, name##__until = (until); name < name##__until; name++)
#define repFromTo(name, from, to) repFromUntil(name, from, to + 1)
#define repr(...)                                                              \\
  __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until)                                       \\
  for (int name = until - 1, name##__from = (from); name >= name##__from;      \\
       name--)
#define reprFromTo(name, from, to) reprFromUntil(name, from, to + 1)

#define debugos cout
#ifdef LOCAL
#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;                                                         \\
    }                                                                          \\
  }
#else
#define debug(v)                                                               \\
  {}
#define debugv(v)                                                              \\
  {}
#define debuga(m, w)                                                           \\
  {}
#define debugaa(m, h, w)                                                       \\
  {}
#endif

#define newl "\\n"

#define all(iter) begin(iter), end(iter)

#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

template <class T> inline bool chmin(T &var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else
    return false;
}
template <class T> inline bool chmax(T &var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else
    return false;
}

class MyScanner {
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 MyScanner &operator>>(char &var) {
    var = c();
    return *this;
  }
  inline MyScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  inline MyScanner &operator>>(ll &var) {
    input_integer<ll>(var);
    return *this;
  }
  inline MyScanner &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;
  }
  inline operator int() {
    int n;
    *this >> n;
    return n;
  }
  inline operator ll() {
    ll n;
    *this >> n;
    return n;
  }

private:
  inline int isvisiblechar(int c) { return 0x21 <= c && c <= 0x7E; }
};
class MyPrinter {
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 MyPrinter &operator<<(char c) {
    putchar_unlocked(c);
    return *this;
  }
  inline MyPrinter &operator<<(int var) {
    output_integer<int>(var);
    return *this;
  }
  inline MyPrinter &operator<<(ll var) {
    output_integer<ll>(var);
    return *this;
  }
  inline MyPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MyPrinter &operator<<(const char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MyPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar_unlocked(*p++);
    return *this;
  }
};
MyScanner IN;
MyPrinter OUT;

int main() {
  int a, b;
  char op;
  while (IN >> a >> op >> b, op != '?')
    OUT << (op == '+'   ? a + b
            : op == '-' ? a - b
            : op == '*' ? a * b
            : op == '/' ? a / b
                        : 0)
        << newl;
}


Error: TLE

Fixed submission:

#ifdef LOCAL
#pragma GCC optimize("O0")
#else
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>

using namespace std;
using namespace std::placeholders;

using ll = long long;
const int INF = 1e9 + 7;
const ll INF_LL = 1e18 + 7;

#define __overload3(_1, _2, _3, name, ...) name
#define rep(...)                                                               \\
  __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until)                                        \\
  for (int name = from, name##__until = (until); name < name##__until; name++)
#define repFromTo(name, from, to) repFromUntil(name, from, to + 1)
#define repr(...)                                                              \\
  __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until)                                       \\
  for (int name = until - 1, name##__from = (from); name >= name##__from;      \\
       name--)
#define reprFromTo(name, from, to) reprFromUntil(name, from, to + 1)

#define debugos cout
#ifdef LOCAL
#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;                                                         \\
    }                                                                          \\
  }
#else
#define debug(v)                                                               \\
  {}
#define debugv(v)                                                              \\
  {}
#define debuga(m, w)                                                           \\
  {}
#define debugaa(m, h, w)                                                       \\
  {}
#endif

#define newl "\\n"

#define all(iter) begin(iter), end(iter)

#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

template <class T> inline bool chmin(T &var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else
    return false;
}
template <class T> inline bool chmax(T &var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else
    return false;
}

class MyScanner {
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 MyScanner &operator>>(char &var) {
    var = c();
    return *this;
  }
  inline MyScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  inline MyScanner &operator>>(ll &var) {
    input_integer<ll>(var);
    return *this;
  }
  inline MyScanner &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;
  }
  inline operator int() {
    int n;
    *this >> n;
    return n;
  }
  inline operator ll() {
    ll n;
    *this >> n;
    return n;
  }

private:
  inline int isvisiblechar(int c) { return 0x21 <= c && c <= 0x7E; }
};
class MyPrinter {
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 MyPrinter &operator<<(char c) {
    putchar_unlocked(c);
    return *this;
  }
  inline MyPrinter &operator<<(int var) {
    output_integer<int>(var);
    return *this;
  }
  inline MyPrinter &operator<<(ll var) {
    output_integer<ll>(var);
    return *this;
  }
  inline MyPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MyPrinter &operator<<(const char *str_p) {
    while (*str_p)
      putchar_unlocked(*(str_p++));
    return *this;
  }
  inline MyPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar_unlocked(*p++);
    return *this;
  }
};
MyScanner IN;
MyPrinter OUT;

int main() {
  int a, b;
  char op;
  while (IN >> a >> b >> op, op != '?')
    OUT << (op == '+'   ? a + b
            : op == '-' ? a - b
            : op == '*' ? a * b
            : op == '/' ? a / b
                        : 0)
        << newl;
}