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  1. #include<bits/stdc++.h>
  2. #define ll long long
  3. #define ull unsigned long long
  4. #define nl '\n'
  5. #define mod 1000000007
  6. #define fori(i,n) for(ll i=0;i < n;i++)
  7. #define forn(i,n) for(ll i=1;i <= n;i++)
  8. #define forx(i,x,n) for(ll i=x;i < n;i++)
  9. #define sortx(x) sort(x.begin(),x.end())
  10. #define sorty(x) sort(x.begin(),x.end(),greater<>())
  11. using namespace std;
  12. /*#include <ext/pb_ds/assoc_container.hpp>
  13. #include <ext/pb_ds/tree_policy.hpp>
  14. using namespace __gnu_pbds;
  15. template<typename T>
  16. using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
  17. using namespace __gnu_pbds;
  18. #define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
  19.  
  20. ll Mod(ll base, ll exp, ll MOD){
  21.     if(exp == 0) return 1;
  22.     ll res = Mod(base,exp/2,MOD);
  23.     if(exp % 2) 
  24.       return (((res * res) % MOD)*base) % MOD;
  25.     else
  26.       return (res*res) % MOD;
  27. }
  28.  
  29. ll gcd(ll x,ll y){
  30.   ll b = min(x,y);
  31.   ll a = max(x,y);
  32.   while(b != 0){
  33.     ll temp = b;
  34.     b = a % b;
  35.     a = temp;
  36.   }
  37.   return a;
  38. }
  39.  
  40. ll div(vector<ll> &x){
  41.   for(ll i=1;i <= 1000007;i++){
  42.     for(ll j=i;j <= 1000007;j+=i){
  43.       x[j]++;
  44.     }
  45.   }
  46. }
  47.  
  48. bool prime(ll n){
  49.   int c=0;
  50.   for(ll i=1;i <= n;i++){
  51.     if(n % i == 0) c++;
  52.     if(c > 2) break;
  53.   }
  54.   if(c == 2) return true;
  55.   return false;
  56. }*/
  57.  
  58. void generatePrimes(int limit, vector<bool> &isPrime) {
  59.     isPrime.assign(limit + 1, true); 
  60.     isPrime[0] = isPrime[1] = false; 
  61.  
  62.     for (int i = 2; i * i <= limit; i++) {
  63.         if (isPrime[i]) {
  64.             for (int j = i * i; j <= limit; j += i) {
  65.                 isPrime[j] = false;
  66.             }
  67.         }
  68.     }
  69. }
  70.  
  71. ll computePrimeSums(ll n, ll &sum, const vector<bool> &isPrime) {
  72.     for (int i = 2; i <= n; i++) {
  73.         sum += (isPrime[i] ? i : 0);
  74.     }
  75.     return sum;
  76. }
  77.  
  78. int main() {
  79.     ios::sync_with_stdio(false);
  80.     cin.tie(nullptr);
  81.  
  82.     const int LIMIT = 100000;
  83.     vector<bool> isPrime(LIMIT + 1, true);
  84.     ll sum=0;
  85.     generatePrimes(LIMIT, isPrime);
  86.     ll n;
  87.     cin >> n;
  88.     computePrimeSums(n, sum, isPrime);
  89.     cout << sum << nl;
  90.     return 0;
  91. }
  92.  
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/r2GjGQ
language:
C++14 (gcc 8.3)
created:
14 days ago
visibility:
public

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