p10.cpp 1.15 KB
/*
Summation of primes
Problem 10

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

*/

#include <stdio.h>
#include <math.h>

#define SIZE_ARRAY 2000000

bool esPrimo(int eval, int *primosConocidos);

int *lastAddr = 0;

int main(int argc, char const *argv[])
{
	int arrayPrime[SIZE_ARRAY] = { 0 };
	int counter;

	long sum = 0;
	bool continuar = true;

	//Agregando valores conocidos
	arrayPrime[0] = 2;
	arrayPrime[1] = 3;

	sum = 5;

	//Init
	counter = 3;
	do
	{
		counter+=2;
		sum += (esPrimo(counter, arrayPrime)) ? counter : 0;

	} while (counter < SIZE_ARRAY);

	printf("Sumatoria:\t%ld\n", sum);

	return 0;
}


bool esPrimo(int eval, int *primosConocidos)
{
	bool valido = true;
	double res = 0;

	res = sqrt(eval);
	while(*primosConocidos != 0)
	{
		if((double) *primosConocidos <= res)
		{
			if ( eval % *primosConocidos == 0 )
			{
				valido = false;
				break;
			}
			else
			{
				primosConocidos++;
			}
		}
		else
		{

			lastAddr = (lastAddr == 0) ? ++primosConocidos : lastAddr + 1;

			primosConocidos = lastAddr;
			*primosConocidos = eval;
			valido = true;
			break;
		}

	}

	return valido;
}