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Criba de Eratostenes - C++
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/* | |
* Criba de Eratostenes - C++ | |
* Copyright 2014 Martin Cruz Otiniano | |
* Description : Esta funcion devuelve un vector(STL) con los numeros primos hasta un rango n enviado como parametro. | |
* Site : martincruz.me | |
*/ | |
#include <iostream> | |
#include <vector> | |
#include <cmath> | |
using namespace std; | |
void mostrar_criba(vector<int> criba) | |
{ | |
cout << endl; | |
for (int i = 0; i < criba.size(); i++) | |
cout << criba[i] << "\t"; | |
cout << endl; | |
} | |
vector<int> criba_eratostenes(int n) | |
{ | |
vector<int> criba; | |
int current_primo; // numero primo que iremos tomando del vector | |
// vector con numeros desde 2 hasta n | |
for (int i = 2; i <= n; i++) | |
criba.push_back(i); | |
if (n == 2 || n == 3) | |
return criba; | |
// iterador para el vector criba | |
vector<int>::iterator it = criba.begin(); | |
current_primo = *it; // El primer primo es el 2 | |
do | |
{ | |
vector<int>::iterator it2 = it + 1; | |
for(; it2 <= criba.end(); it2++) | |
if(*it2 % current_primo == 0) | |
criba.erase(it2); | |
it++; | |
current_primo = *it; | |
} while (pow(current_primo, 2) < n); | |
return criba; | |
} | |
int main() | |
{ | |
int n; // Limite de criba | |
vector<int> num_primos; | |
cout << "Numero limite de numeros: "; | |
cin >> n; | |
num_primos = criba_eratostenes(n); | |
mostrar_criba(num_primos); | |
return 0; | |
} |
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