Problem p02983 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define Abs(x) ((x) < 0 ? (x) * -1 : (x))

#define rep(x, y) for ((x) = 0; (x) < (y); (x)++)
#define repin(x, y) for ((x) = 0; (x) <= (y); (x)++)
#define nep(x, y) for ((x) = (y)-1; 0 <= (x); (x)--)
#define nepi(x, y, z) for ((x) = (y)-1; (z) <= (x); (x)--)
#define repi(x, y, z) for ((x) = (z); (x) < (y); (x)++)
#define repiin(x, y, z) for ((x) = (z); (x) <= (y); (x)++)
#define reps(x, y, z) for ((x) = 0; (x) < (y); (x) += (z))
#define repis(x, y, z, s) for ((x) = (z); (x) < (y); (x) += (s))
#define repiins(x, y, z, s) for ((x) = (z); (x) <= (y); (x) += (s))
#define repit(x)                                                               \
  for (__typeof((x).begin()) it = (x).begin(); it != (x).end(); it++)
#define repit2(x)                                                              \
  for (__typeof((x).begin()) it2 = (x).begin(); it2 != (x).end(); it2++)
#define nepit(x)                                                               \
  for (__typeof((x).rbegin()) it = (x).rbegin(); it != (x).rend(); it++)

#define All(x) (x).begin(), (x).end()

#define Mem0(x) memset(x, 0, sizeof(x))
#define Mem1(x) memset(x, -1, sizeof(x))

// can be applied to string type
#define Unique(v) v.resize(unique(All(v)) - v.begin())

#define peq(p0, p1) (p0.first == p1.first && p0.second == p1.second)

#define End '\n'
#define Out(x) cout << (x) << End
template <typename T> void OutN(T x) {
  size_t i, len = x.size() - 1;

  for (i = 0; i < len; i++)
    cout << x[i] << " ";
  cout << x[len] << '\n';
}
#define OutaN(x)                                                               \
  do {                                                                         \
    size_t i, len = sizeof(x) / sizeof(__typeof(x[0])) - 1;                    \
    for (i = 0; i < len; i++)                                                  \
      cout << x[i] << " ";                                                     \
    cout << x[len] << '\n';                                                    \
  } while (0);

template <typename T> void Outit(T x) {
  auto end = x.end();

  end--;

  for (auto it = x.begin(); it != end; it++)
    cout << *it << " ";
  cout << *end << '\n';
}
template <typename T> void Debug(const T &val) { cerr << val << End; }
template <typename T, typename... Args> void Debug(const T &val, Args... args) {
  cerr << val << ' ';
  Debug(std::forward<Args>(args)...);
}

template <typename T> inline bool Max(T &x, const T &y) {
  return x < y ? x = y, 1 : 0;
}
template <typename T> inline bool Min(T &x, const T &y) {
  return x > y ? x = y, 1 : 0;
}
template <typename T> using V = vector<T>;
template <typename T> using VV = V<V<T>>;

// can be applied to string type
#define Sort(v) sort(All(v))
#define SortR(v) sort(All(v), std::greater<__typeof(v[0])>())
// array sorters
#define Sart(a) sort(a, a + sizeof(a) / sizeof(__typeof(a[0])));
#define SartR(a)                                                               \
  sort(a, a + sizeof(a) / sizeof(__typeof(a[0])),                              \
       std::greater<__typeof(a[0])>())

#define pb push_back
#define mp make_pair
#define a first
#define b second
#define lb std::lower_bound
#define ub std::upper_bound

#define lbi(v, x) lb(All(v), (x)) - v.begin()
#define ubi(v, x) ub(All(v), (x)) - v.begin()

static const ll MOD = 1e9 + 7;
static const double PI = 3.141592653589793;

#define LOCAL 0

int main() {
#if LOCAL
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
  freopen("debug.txt", "w", stderr);
#endif

  cin.tie(0);
  ios::sync_with_stdio(false);
  // std::cout.precision(18);

  ll l, r;

  cin >> l >> r;

  if (l == 0) {
    Out(0);
  } else if (l + 1 == r) {
    Out((l * r) % 2019);
  } else {
    map<int, ll> table;
    V<pair<int, ll>> v;
    int ans = INT_MAX;

    ll i, j, len;

    repiin(i, r, l) table[i % 2019]++;
    repit(table) v.pb(*it);

    len = v.size();
    rep(i, len) {
      if (1 < v[i].b)
        Min(ans, (v[i].a * v[i].a) % 2019);

      repi(j, len, i + 1) Min(ans, (v[i].a * v[j].a) % 2019);
    }

    Out(ans);
  }

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define Abs(x) ((x) < 0 ? (x) * -1 : (x))

#define rep(x, y) for ((x) = 0; (x) < (y); (x)++)
#define repin(x, y) for ((x) = 0; (x) <= (y); (x)++)
#define nep(x, y) for ((x) = (y)-1; 0 <= (x); (x)--)
#define nepi(x, y, z) for ((x) = (y)-1; (z) <= (x); (x)--)
#define repi(x, y, z) for ((x) = (z); (x) < (y); (x)++)
#define repiin(x, y, z) for ((x) = (z); (x) <= (y); (x)++)
#define reps(x, y, z) for ((x) = 0; (x) < (y); (x) += (z))
#define repis(x, y, z, s) for ((x) = (z); (x) < (y); (x) += (s))
#define repiins(x, y, z, s) for ((x) = (z); (x) <= (y); (x) += (s))
#define repit(x)                                                               \
  for (__typeof((x).begin()) it = (x).begin(); it != (x).end(); it++)
#define repit2(x)                                                              \
  for (__typeof((x).begin()) it2 = (x).begin(); it2 != (x).end(); it2++)
#define nepit(x)                                                               \
  for (__typeof((x).rbegin()) it = (x).rbegin(); it != (x).rend(); it++)

#define All(x) (x).begin(), (x).end()

#define Mem0(x) memset(x, 0, sizeof(x))
#define Mem1(x) memset(x, -1, sizeof(x))

// can be applied to string type
#define Unique(v) v.resize(unique(All(v)) - v.begin())

#define peq(p0, p1) (p0.first == p1.first && p0.second == p1.second)

#define End '\n'
#define Out(x) cout << (x) << End
template <typename T> void OutN(T x) {
  size_t i, len = x.size() - 1;

  for (i = 0; i < len; i++)
    cout << x[i] << " ";
  cout << x[len] << '\n';
}
#define OutaN(x)                                                               \
  do {                                                                         \
    size_t i, len = sizeof(x) / sizeof(__typeof(x[0])) - 1;                    \
    for (i = 0; i < len; i++)                                                  \
      cout << x[i] << " ";                                                     \
    cout << x[len] << '\n';                                                    \
  } while (0);

template <typename T> void Outit(T x) {
  auto end = x.end();

  end--;

  for (auto it = x.begin(); it != end; it++)
    cout << *it << " ";
  cout << *end << '\n';
}
template <typename T> void Debug(const T &val) { cerr << val << End; }
template <typename T, typename... Args> void Debug(const T &val, Args... args) {
  cerr << val << ' ';
  Debug(std::forward<Args>(args)...);
}

template <typename T> inline bool Max(T &x, const T &y) {
  return x < y ? x = y, 1 : 0;
}
template <typename T> inline bool Min(T &x, const T &y) {
  return x > y ? x = y, 1 : 0;
}
template <typename T> using V = vector<T>;
template <typename T> using VV = V<V<T>>;

// can be applied to string type
#define Sort(v) sort(All(v))
#define SortR(v) sort(All(v), std::greater<__typeof(v[0])>())
// array sorters
#define Sart(a) sort(a, a + sizeof(a) / sizeof(__typeof(a[0])));
#define SartR(a)                                                               \
  sort(a, a + sizeof(a) / sizeof(__typeof(a[0])),                              \
       std::greater<__typeof(a[0])>())

#define pb push_back
#define mp make_pair
#define a first
#define b second
#define lb std::lower_bound
#define ub std::upper_bound

#define lbi(v, x) lb(All(v), (x)) - v.begin()
#define ubi(v, x) ub(All(v), (x)) - v.begin()

static const ll MOD = 1e9 + 7;
static const double PI = 3.141592653589793;

#define LOCAL 0

int main() {
#if LOCAL
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
  freopen("debug.txt", "w", stderr);
#endif

  cin.tie(0);
  ios::sync_with_stdio(false);
  // std::cout.precision(18);

  ll l, r;

  cin >> l >> r;

  if (l == 0) {
    Out(0);
  } else if (l + 1 == r) {
    Out((l * r) % 2019);
  } else {
    map<int, ll> table;
    V<pair<int, ll>> v;
    int ans = INT_MAX;

    ll i, j, len;

    repiin(i, r, l) {
      if (i % 2019 == 0) {
        Out(0);

        return 0;
      }

      table[i % 2019]++;
    }
    repit(table) v.pb(*it);

    len = v.size();
    rep(i, len) {
      if (1 < v[i].b)
        Min(ans, (v[i].a * v[i].a) % 2019);

      repi(j, len, i + 1) Min(ans, (v[i].a * v[j].a) % 2019);
    }

    Out(ans);
  }

  return 0;
}