Problem p02624 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdint>
#include <cstdlib>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <stdio.h>
#include <string>
#include <tuple>
#include <vector>

using namespace std;

template <class T> using V = vector<T>;

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

const long long INF = 1LL << 60;
const double pi = acos(-1);

using ll = long long;
using db = long double;
using st = string;
using ch = char;
using vll = V<ll>;
using vpll = V<pair<ll, ll>>;
using vst = V<st>;
using vdb = V<db>;
using vch = V<ch>;
using graph = V<V<int>>;
using pq = priority_queue<ll>;

#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define bgn begin()
#define en end()
#define SORT(a) sort((a).bgn, (a).en)
#define REV(a) reverse((a).bgn, (a).en)
#define fi first
#define se second
#define sz size()
#define gcd(a, b) __gcd(a, b)
#define pb(a) push_back(a);
#define ALL(a) (a).begin(), (a).end()

ll Sum(ll n) {
  ll m = 0;
  while (n) {
    m += n % 10;
    n /= 10;
  }
  return m;
}

const int MAX = 510000;
// change
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

void Comuse() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

#define comuse Comuse()

ll combi(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

ll perm(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] % MOD) % MOD;
}

ll modpow(ll a, ll n, ll mod) {
  ll ans = 1;
  while (n > 0) {
    if (n & 1) {
      ans = ans * a % mod;
    }

    a = a * a % mod;

    n >>= 1;
  }

  return ans;
}

ll modinv(ll a, ll mod) { return modpow(a, mod - 2, mod); }

ll modcombi(int n, int k, int mod) {
  ll ans = 1;
  for (ll i = n; i > n - k; i--) {
    ans *= i;
    ans %= mod;
  }
  for (ll i = 1; i <= k; i++) {
    ans *= modinv(i, mod);
    ans %= mod;
  }

  return ans;
}

ll lcm(ll a, ll b) {
  ll n;
  n = a / gcd(a, b) * b;
  return n;
}

vll div(ll n) {
  vll ret;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i * i != n) {
        ret.push_back(n / i);
      }
    }
  }
  SORT(ret);
  return (ret);
}

vector<bool> isprime(MAX + 100, true);

void primeuse() {
  isprime[0] = false;
  isprime[1] = false;
  for (int i = 2; i < MAX + 50; i++) {
    int up = sqrt(i) + 1;
    for (int j = 2; j < up; j++) {
      if (i % j == 0) {
        isprime[i] = false;
      }
    }
  }
}

void bf(ll n, string s) {
  for (ll i = 0; i < n; i++) {
    cout << s;
  }
  cout << "\\n";
}

void Solve();

const int MAX_N = 131072;
// segment tree
int NN;
int seg[MAX_N * 2 - 1];
void seguse() {
  for (int i = 0; i < 2 * NN - 1; i++) {
    seg[i] = INT_MAX;
  }
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(20) << fixed;
  Solve();
}

/****************************************\\
| Thank you for viewing my code:)        |
| Written by RedSpica a.k.a. RanseMirage |
| Twitter:@asakaakasaka                  |
\\****************************************/
// segtreeの葉の先頭の添え字はN-1
void Solve() {
  ll n;
  cin >> n;
  vll A(n + 100);
  for (int i = 1; i <= n; i++) {
    for (int j = i; j <= n + 10; j += i) {
      A[j]++;
    }
  }

  ll ans = 0;
  FOR(i, 0, n + 1) { ans += A[i] * i; }

  cout << ans << "\\n";
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdint>
#include <cstdlib>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <stdio.h>
#include <string>
#include <tuple>
#include <vector>

using namespace std;

template <class T> using V = vector<T>;

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

const long long INF = 1LL << 60;
const double pi = acos(-1);

using ll = long long;
using db = long double;
using st = string;
using ch = char;
using vll = V<ll>;
using vpll = V<pair<ll, ll>>;
using vst = V<st>;
using vdb = V<db>;
using vch = V<ch>;
using graph = V<V<int>>;
using pq = priority_queue<ll>;

#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define bgn begin()
#define en end()
#define SORT(a) sort((a).bgn, (a).en)
#define REV(a) reverse((a).bgn, (a).en)
#define fi first
#define se second
#define sz size()
#define gcd(a, b) __gcd(a, b)
#define pb(a) push_back(a);
#define ALL(a) (a).begin(), (a).end()

ll Sum(ll n) {
  ll m = 0;
  while (n) {
    m += n % 10;
    n /= 10;
  }
  return m;
}

const int MAX = 510000;
// change
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

void Comuse() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

#define comuse Comuse()

ll combi(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

ll perm(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] % MOD) % MOD;
}

ll modpow(ll a, ll n, ll mod) {
  ll ans = 1;
  while (n > 0) {
    if (n & 1) {
      ans = ans * a % mod;
    }

    a = a * a % mod;

    n >>= 1;
  }

  return ans;
}

ll modinv(ll a, ll mod) { return modpow(a, mod - 2, mod); }

ll modcombi(int n, int k, int mod) {
  ll ans = 1;
  for (ll i = n; i > n - k; i--) {
    ans *= i;
    ans %= mod;
  }
  for (ll i = 1; i <= k; i++) {
    ans *= modinv(i, mod);
    ans %= mod;
  }

  return ans;
}

ll lcm(ll a, ll b) {
  ll n;
  n = a / gcd(a, b) * b;
  return n;
}

vll div(ll n) {
  vll ret;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i * i != n) {
        ret.push_back(n / i);
      }
    }
  }
  SORT(ret);
  return (ret);
}

vector<bool> isprime(MAX + 100, true);

void primeuse() {
  isprime[0] = false;
  isprime[1] = false;
  for (int i = 2; i < MAX + 50; i++) {
    int up = sqrt(i) + 1;
    for (int j = 2; j < up; j++) {
      if (i % j == 0) {
        isprime[i] = false;
      }
    }
  }
}

void bf(ll n, string s) {
  for (ll i = 0; i < n; i++) {
    cout << s;
  }
  cout << "\\n";
}

void Solve();

const int MAX_N = 131072;
// segment tree
int NN;
int seg[MAX_N * 2 - 1];
void seguse() {
  for (int i = 0; i < 2 * NN - 1; i++) {
    seg[i] = INT_MAX;
  }
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(20) << fixed;
  Solve();
}

/****************************************\\
| Thank you for viewing my code:)        |
| Written by RedSpica a.k.a. RanseMirage |
| Twitter:@asakaakasaka                  |
\\****************************************/
// segtreeの葉の先頭の添え字はN-1
void Solve() {
  ll n;
  cin >> n;
  ll ans = 0;
  for (ll i = 1; i <= n; i++) {
    int d = 1;
    int now = i;
    for (int j = 2; j * j <= i; j++) {
      int count = 1;
      while (now % j == 0) {
        count++;
        now /= j;
      }
      d *= count;
    }
    if (now != 1) {
      d *= 2;
    }
    ans += d * i;
  }
  cout << ans << "\\n";
}