Prime number Screening Method

The prime number is the problem that comes up frequently, judging whether a count is a prime, basically everyone will, but if it is a large range of prime, the common method for easy time-out, so you can use the template, the prime number to play the table.

1 //Number of primes within 10 million2#include <iostream>3#include <cstdio>4#include <cstring>5 using namespacestd;6 inta[10000005];7 voidSushu ()8 {9Memset (A,0,sizeof(a));//all numbers are marked as 0,0, and 1 for non-prime numbersTena[0]=1, a[1]=1;//0,1 marked as non-prime One      for(intI=2; i<=5000000; i++) A     { -         if(!A[i]) -              for(intJ=i+i; j<=10000000; J+=i)//each number consisting of prime numbers must not be primes. the             { -a[j]=1; -             } -     } +      for(intI=1; i<= +; i++) -         if(!A[i]) +printf"%d", i); A } at intMain () - { - Sushu (); -}

Prime number Screening Method