Problem p03418 (C++)

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

using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
typedef vector<vector<ll>> mat;
typedef vector<ll> vec;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
const ll mod = 1000000007;
const ll INF = mod * mod;
const ld eps = 1e-12;
const ld pi = acos(-1.0);
// int qp(int a,ll b){int
// ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
ll qp(ll a, ll b, int mo) {
  int ans = 1;
  do {
    if (b & 1)
      ans = 1ll * ans * a % mo;
    a = 1ll * a * a % mo;
  } while (b >>= 1);
  return ans;
}
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; } // 最大公約数
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }     // 最小公倍数
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec)
    is >> v;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) {
  os << "deq[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &pa) {
  os << "(" << pa.first << "," << pa.second << ")";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template <typename T, typename... Args>
void ndarray(vector<T> &vec, int len, Args... args) {
  vec.resize(len);
  for (auto &v : vec)
    ndarray(v, args...);
}
template <typename T> bool chmax(T &m, const T q) {
  if (m < q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T> bool chmin(T &m, const T q) {
  if (q < m) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first + r.first, l.second + r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first - r.first, l.second - r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator<(const pair<T1, T2> l, const pair<T1, T2> r) {
  return (l.first < r.first);
}
template <typename T1, typename T2>
pair<T1, T2> operator>(const pair<T1, T2> l, const pair<T1, T2> r) {
  return (l.first > r.first);
}

void solve() {
  ll N, K;
  cin >> N >> K;
  ll res = 0;

  for (ll i = 1; i <= N; ++i) {
    for (ll j = i; j <= N; ++j) {
      if (i % j >= K) {
        res++;
        // cout << "(" << i << ", " << j << ")" << endl;
      }
      if ((i != j) && (j % i >= K)) {
        res++;
        // cout << "(" << j << ", " << i << ")" << endl;
      }
    }
  }

  cout << res << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  std::cout << fixed << setprecision(10);
  solve();
  return 0;
}


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

using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
typedef vector<vector<ll>> mat;
typedef vector<ll> vec;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
const ll mod = 1000000007;
const ll INF = mod * mod;
const ld eps = 1e-12;
const ld pi = acos(-1.0);
// int qp(int a,ll b){int
// ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}
ll qp(ll a, ll b, int mo) {
  int ans = 1;
  do {
    if (b & 1)
      ans = 1ll * ans * a % mo;
    a = 1ll * a * a % mo;
  } while (b >>= 1);
  return ans;
}
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; } // 最大公約数
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }     // 最小公倍数
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

template <typename T> istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec)
    is >> v;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) {
  os << "deq[";
  for (auto v : vec)
    os << v << ",";
  os << "]";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) {
  os << "{";
  for (auto v : vec)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &pa) {
  os << "(" << pa.first << "," << pa.second << ")";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename TK, typename TV>
ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) {
  os << "{";
  for (auto v : mp)
    os << v.first << "=>" << v.second << ",";
  os << "}";
  return os;
}
template <typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template <typename T, typename... Args>
void ndarray(vector<T> &vec, int len, Args... args) {
  vec.resize(len);
  for (auto &v : vec)
    ndarray(v, args...);
}
template <typename T> bool chmax(T &m, const T q) {
  if (m < q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T> bool chmin(T &m, const T q) {
  if (q < m) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first + r.first, l.second + r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first - r.first, l.second - r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator<(const pair<T1, T2> l, const pair<T1, T2> r) {
  return (l.first < r.first);
}
template <typename T1, typename T2>
pair<T1, T2> operator>(const pair<T1, T2> l, const pair<T1, T2> r) {
  return (l.first > r.first);
}

void solve() {
  ll N, K;
  cin >> N >> K;
  ll res = 0;

  if (K == 0) {
    res = N * N;
  } else {
    for (ll i = 1; i <= N; ++i) {
      ll dif = (N / i);
      dif *= max(0LL, i - K);

      dif += max(0LL, N % i - K + 1);

      res += dif;
    }
  }

  cout << res << endl;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  std::cout << fixed << setprecision(10);
  solve();
  return 0;
}