text: Segmented Sieve | This functions finds all primes smaller than ' limit ' using simple sieve of eratosthenes . ; Create a boolean array " mark [ 0 . . limit - 1 ] " and initialize all entries of it as true . A value in mark [ p ] will finally be false if ' p ' is Not a prime , else true . ; One by one traverse all numbers so that their multiples can be marked as composite . ; If p is not changed , then it is a prime ; Update all multiples of p ; Print all prime numbers and store them in prime
code: void simpleSieve ( int limit ) { bool mark [ limit ] ; for ( int i = 0 ; i < limit ; i ++ ) { mark [ i ] = true ; } for ( int p = 2 ; p * p < limit ; p ++ ) { if ( mark [ p ] == true ) { for ( int i = p * p ; i < limit ; i += p ) mark [ i ] = false ; } } for ( int p = 2 ; p < limit ; p ++ ) if ( mark [ p ] == true ) cout << p << " ▁ " ; }