Problem p02548 (C++) — buggy submission, verdict: Time Limit Exceeded

#pragma GCC optimize("O3")
#pragma GCC target("sse4")

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define ins insert

template <class T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }

// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int MOD = 1000000007;
const char nl = '\\n';
const int MX = 100001; // check the limits, dummy
const char sp = ' ';
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ll n;
  cin >> n;
  ll i, j;
  int count = 0;
  for (i = 1; i <= n; i++) {
    for (j = 1; i * j < n; j++) {
      count++;
    }
  }
  cout << count;
  return 0;
}

// read the question correctly (ll vs int)
// template by bqi343


Error: TLE

Fixed submission:

#pragma GCC optimize("O3")
#pragma GCC target("sse4")

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define ins insert

template <class T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }

// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int MOD = 1000000007;
const char nl = '\\n';
const int MX = 100001; // check the limits, dummy
const char sp = ' ';
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ll n;
  cin >> n;
  ll i, j, k;
  ll count = 0;
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= n; j++) {
      if (i * j < n)
        count++;
    }
  }
  cout << count;
  return 0;
}

// read the question correctly (ll vs int)
// template by bqi343