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

#include <bits/stdc++.h>

using namespace std;

#define LL long long
#define DD double
#define Pb push_back
#define Bp pop_back
#define Pf push_front
#define Fp pop_front
#define Ub upper_bound
#define Lb lower_bound
#define In insert
#define All(x) x.begin(), x.end()
#define mem(a, b) memset(a, b, sizeof(a))
#define fast                                                                   \\
  ios_base::sync_with_stdio(0);                                                \\
  cin.tie(0)
#define X first
#define Y second
#define mx1 10
#define mx2 110
#define mx3 1010
#define mx4 10010
#define mx5 100010
#define mx6 1000010
#define mx7 10000010

typedef vector<LL> Vl;
typedef vector<DD> Vd;
typedef vector<bool> Vb;
typedef vector<Vl> VVl;
typedef pair<LL, LL> Pll;
typedef pair<DD, DD> Pdd;
typedef vector<Pll> Vpl;
typedef vector<Pdd> Vpd;
typedef queue<LL> Ql;
typedef stack<LL> Sl;
typedef deque<LL> Dl;

LL _set(LL N, LL pos) { return N = N | (1 << pos); }
LL _reset(LL N, LL pos) { return N = N & ~(1 << pos); }
bool _check(LL N, LL pos) { return (bool)(N & (1 << pos)); }
bool _upper(char a) { return a >= 'A' && a <= 'Z'; }
bool _lower(char a) { return a >= 'a' && a <= 'z'; }
bool _digit(char a) { return a >= '0' && a <= '9'; }

LL dx[] = {1, -1, 0, 0, -1, -1, 1, 1};
LL dy[] = {0, 0, 1, -1, -1, 1, -1, 1};

///**************************DONE****************************///

int cnt[mx7];

int main() {
  LL n;
  cin >> n;

  for (int i = 1; i <= n; i++) {
    for (int j = i; j <= n; j += i)
      cnt[j]++;
  }

  LL ans = 0;
  for (int i = 1; i <= n; i++) {
    ans += 1ll * i * cnt[i];
  }

  cout << ans << '\\n';
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

#define LL long long
#define DD double
#define Pb push_back
#define Bp pop_back
#define Pf push_front
#define Fp pop_front
#define Ub upper_bound
#define Lb lower_bound
#define In insert
#define All(x) x.begin(), x.end()
#define mem(a, b) memset(a, b, sizeof(a))
#define fast                                                                   \\
  ios_base::sync_with_stdio(0);                                                \\
  cin.tie(0)
#define X first
#define Y second
#define mx1 10
#define mx2 110
#define mx3 1010
#define mx4 10010
#define mx5 100010
#define mx6 1000010
#define mx7 10000010

typedef vector<LL> Vl;
typedef vector<DD> Vd;
typedef vector<bool> Vb;
typedef vector<Vl> VVl;
typedef pair<LL, LL> Pll;
typedef pair<DD, DD> Pdd;
typedef vector<Pll> Vpl;
typedef vector<Pdd> Vpd;
typedef queue<LL> Ql;
typedef stack<LL> Sl;
typedef deque<LL> Dl;

LL _set(LL N, LL pos) { return N = N | (1 << pos); }
LL _reset(LL N, LL pos) { return N = N & ~(1 << pos); }
bool _check(LL N, LL pos) { return (bool)(N & (1 << pos)); }
bool _upper(char a) { return a >= 'A' && a <= 'Z'; }
bool _lower(char a) { return a >= 'a' && a <= 'z'; }
bool _digit(char a) { return a >= '0' && a <= '9'; }

LL dx[] = {1, -1, 0, 0, -1, -1, 1, 1};
LL dy[] = {0, 0, 1, -1, -1, 1, -1, 1};

///**************************DONE****************************///

bool prime[mx7];
vector<LL> P;

void sv(LL n) {
  for (LL i = 2; i * i <= n; i++) {
    if (!prime[i]) {
      for (LL j = i * i; j <= n; j += i)
        prime[j] = true;
    }
  }

  for (LL i = 2; i <= n; i++)
    if (!prime[i])
      P.Pb(i);
}

int main() {

  LL n;
  cin >> n;
  sv(n);

  vector<map<LL, LL>> mp(n + 5);

  for (auto p : P) {
    LL t = p;
    while (1) {
      for (LL i = t; i <= n; i += t)
        mp[i][p]++;

      if (t * p > n)
        break;

      t *= p;
    }
  }

  LL ans = 0;

  for (int i = 1; i <= n; i++) {
    LL x = 1;
    for (auto j : mp[i]) {
      x *= (j.Y + 1);
    }
    ans += i * x;
  }

  cout << ans << '\\n';
  return 0;
}