Problem p02548 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
#define ll long long
#define dd double
#define MOD1 1000000007
#define MOD2 998244353
#define nl cout << endl
#define rt ll Q[100005] = {0}
#define mp make_pair
#define test()                                                                 \
  ll t;                                                                        \
  cin >> t;                                                                    \
  while (t--)
#define pb push_back
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define s(ar, n) sort(ar, ar + n)
#define rs(ar, n) sort(ar, ar + n, greater<ll>())
#define oa(a, n)                                                               \
  for (ll i = 0; i < n; i++)                                                   \
    cout << a[i] << " ";                                                       \
  nl
#define cn(a, n)                                                               \
  for (ll i = 0; i < n; i++)                                                   \
    cin >> a[i];
#define ov(a, n)                                                               \
  for (ll i = n - 1; i >= 0; i--)                                              \
    cout << a[i] << " ";                                                       \
  nl
#define ovp(a, n)                                                              \
  for (ll i = 0; i < n; i++)                                                   \
    cout << a[i].ff << " " << a[i].ss << endl;
#define maxa(ar, N) *max_element(ar, ar + N)
#define mina(ar, N) *min_element(ar, ar + N)
#define fastio()                                                               \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
typedef pair<ll, ll> pii;
ll powe(ll n, ll m) {
  if (m == 0)
    return 1;
  ll t = powe(n, m / 2);
  if (m % 2 == 0)
    return (t * t);
  return (((t * t)) * n);
}
ll mpowe(ll n, ll m, ll MOD) {
  if (m == 0)
    return 1;
  ll t = mpowe(n, m / 2, MOD);
  t %= MOD;
  if (m % 2 == 0)
    return (t * t) % MOD;
  return (((t * t) % MOD) * n) % MOD;
}
ll logtwo(ll n) {
  if (n == 1)
    return 0;
  if (n == 0)
    return -1;
  return logtwo(n / 2) + 1;
}
int main() {
  fastio();

  ll n;
  cin >> n;
  ll ans = 1;
  for (int i = 2; i < n; i++) {
    ll temp = 1, x = i;
    for (int j = 2; j * j <= i; j++) {
      ll c = 0;
      if (x % j == 0) {
        while (x % j == 0) {
          c++;
          x = x / j;
        }
        temp *= (c + 1);
      }
    }
    if (x > 1)
      temp *= 2;
    // cout<<i<<" "<<temp<<endl;
    ans += temp;
  }
  cout << ans << endl;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
#define ll long long
#define dd double
#define MOD1 1000000007
#define MOD2 998244353
#define nl cout << endl
#define rt ll Q[100005] = {0}
#define mp make_pair
#define test()                                                                 \
  ll t;                                                                        \
  cin >> t;                                                                    \
  while (t--)
#define pb push_back
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define s(ar, n) sort(ar, ar + n)
#define rs(ar, n) sort(ar, ar + n, greater<ll>())
#define oa(a, n)                                                               \
  for (ll i = 0; i < n; i++)                                                   \
    cout << a[i] << " ";                                                       \
  nl
#define cn(a, n)                                                               \
  for (ll i = 0; i < n; i++)                                                   \
    cin >> a[i];
#define ov(a, n)                                                               \
  for (ll i = n - 1; i >= 0; i--)                                              \
    cout << a[i] << " ";                                                       \
  nl
#define ovp(a, n)                                                              \
  for (ll i = 0; i < n; i++)                                                   \
    cout << a[i].ff << " " << a[i].ss << endl;
#define maxa(ar, N) *max_element(ar, ar + N)
#define mina(ar, N) *min_element(ar, ar + N)
#define fastio()                                                               \
  ios_base::sync_with_stdio(0);                                                \
  cin.tie(0);                                                                  \
  cout.tie(0)
typedef pair<ll, ll> pii;
ll powe(ll n, ll m) {
  if (m == 0)
    return 1;
  ll t = powe(n, m / 2);
  if (m % 2 == 0)
    return (t * t);
  return (((t * t)) * n);
}
ll mpowe(ll n, ll m, ll MOD) {
  if (m == 0)
    return 1;
  ll t = mpowe(n, m / 2, MOD);
  t %= MOD;
  if (m % 2 == 0)
    return (t * t) % MOD;
  return (((t * t) % MOD) * n) % MOD;
}
ll logtwo(ll n) {
  if (n == 1)
    return 0;
  if (n == 0)
    return -1;
  return logtwo(n / 2) + 1;
}
int main() {
  fastio();

  ll n;
  cin >> n;
  ll ans = 1;
  for (int i = 2; i < n; i++) {
    ll temp = 1, x = i;
    for (int j = 2; j * j <= x; j++) {
      ll c = 0;
      if (x % j == 0) {
        while (x % j == 0) {
          c++;
          x = x / j;
        }
        temp *= (c + 1);
      }
    }
    if (x > 1)
      temp *= 2;
    // cout<<i<<" "<<temp<<endl;
    ans += temp;
  }
  cout << ans << endl;
}