Cod sursa(job #2222308)
Utilizator | vadim pislari vadim171098 | Data | 16 iulie 2018 20:45:40 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.56 kb |
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ifstream in;
in.open("ciur.in");
ofstream out;
out.open("ciur.out");
int nr,i,j,sum = 0;
in >> nr;
int *arr = new int[nr];
arr[0] = 1;
arr[1] = 1;
if(sum>=2)sum++;
for(i = 4; i <=nr; i+=2){
arr[i] = 1;
}
for(i = 3; i <=nr; i+=2){
if(arr[i] == 0){
sum++;
for( j = 2; j * i <= nr; j++){
arr[j*i]=1;
}
}
}
out<< sum<<endl;
return 0;
}