June 2018 Update

Task/Semiprime/Factor/semiprime-1.factor

@@ -0,0 +1,4 @@
+USING: kernel math.combinatorics math.primes.factors sequences ;
+: semiprime? ( n -- ? )
+    [ factors 2 <combinations> [ product ] map ]
+    [ [ = ] curry ] bi any? ;

Task/Semiprime/Factor/semiprime-2.factor

@@ -0,0 +1 @@
+100 iota [ semiprime? ] filter [ pprint bl ] each nl

Task/Semiprime/Julia/semiprime.julia

@@ -1 +1,3 @@
-semiprime(n) = sum(values(factor(n))) == 2
+using Primes
+issemiprime(n::Integer) = sum(values(factor(n))) == 2
+@show filter(issemiprime, 1:100)

Task/Semiprime/Lingo/semiprime-1.lingo

@@ -0,0 +1,13 @@
+on isSemiPrime (n)
+    div = 2
+    cnt = 0
+    repeat while cnt < 3 and n <> 1
+        if n mod div = 0 then
+            n = n / div
+            cnt = cnt + 1
+        else
+            div = div + 1
+        end if
+    end repeat
+    return cnt=2
+end

Task/Semiprime/Lingo/semiprime-2.lingo

@@ -0,0 +1,5 @@
+res = []
+repeat with i = 1 to 100
+    if isSemiPrime(i) then res.add(i)
+end repeat
+put res

Task/Semiprime/Perl-6/semiprime-1.pl6

@@ -1,12 +1,11 @@
 sub is-semiprime (Int $n --> Bool) {
     not $n.is-prime and
         .is-prime given
-        $n div first $n %% *,
-            grep &is-prime, 2 .. *;
+        $n div first $n %% *, flat grep &is-prime, 2 .. *;
 }
 
 use Test;
-my @primes = grep &is-prime, 2 .. 100;
+my @primes = flat grep &is-prime, 2 .. 100;
 for ^5 {
     nok is-semiprime([*] my @f1 = @primes.roll(1)), ~@f1;
     ok  is-semiprime([*] my @f2 = @primes.roll(2)), ~@f2;

Task/Semiprime/Perl-6/semiprime-2.pl6

@@ -25,7 +25,7 @@ sub find-factor ( Int $n, $constant = 1 ) {
 INIT my $start = now;
 
 # Infinite list of semiprimes
-constant @semiprimes = 4, 6, 9, -> $p { ($p + 1 ... &is-semiprime).tail } ... *;
+constant @semiprimes = lazy gather for 4 .. * { .take if .&is-semiprime };
 
 # Show the semiprimes < 100
 say 'Semiprimes less than 100:';
@@ -33,6 +33,6 @@ say @semiprimes[^ @semiprimes.first: * > 100, :k ], "\n";
 
 # Check individual integers, or in this case, a range
 my $s = 2⁹⁷ - 1;
-say "Is $_ semiprime?: ", is-semiprime( $_ ) for $s .. $s + 30;
+say "Is $_ semiprime?: ", .&is-semiprime for $s .. $s + 30;
 
 say 'elapsed seconds: ', now - $start;

Task/Semiprime/Ring/semiprime.ring

@@ -17,7 +17,7 @@ next
 func isPrime n
      if n < 2 return false ok
      if n < 4 return true ok
-     if n % 2 = 0 return false ok
+     if n % 2 = 0 and n != 2 return false ok
      for d = 3 to sqrt(n) step 2
          if n % d = 0 return false ok
      next	

Task/Semiprime/Ruby/semiprime.rb

@@ -3,7 +3,7 @@ require 'prime'
 
 class Integer
   def semi_prime?
-    prime_division.map( &:last ).inject( &:+ ) == 2
+    prime_division.map( &:last ).sum == 2
   end
 end
 

Task/Semiprime/Rust/semiprime.rust

@@ -0,0 +1,56 @@
+extern crate primal;
+
+fn isqrt(n: usize) -> usize {
+    (n as f64).sqrt() as usize
+}
+
+fn is_semiprime(mut n: usize) -> bool {
+    let root = isqrt(n) + 1;
+    let primes1 = primal::Sieve::new(root);
+    let mut count = 0;
+
+    for i in primes1.primes_from(2).take_while(|&x| x < root) {
+        while n % i == 0 {
+            n /= i;
+            count += 1;
+        }
+        if n == 1 {
+            break;
+        }
+    }
+
+    if n != 1 {
+        count += 1;
+    }
+    count == 2
+}
+
+#[test]
+fn test1() {
+    assert_eq!((2..10).filter(|&n| is_semiprime(n)).count(), 3);
+}
+
+#[test]
+fn test2() {
+    assert_eq!((2..100).filter(|&n| is_semiprime(n)).count(), 34);
+}
+
+#[test]
+fn test3() {
+    assert_eq!((2..1_000).filter(|&n| is_semiprime(n)).count(), 299);
+}
+
+#[test]
+fn test4() {
+    assert_eq!((2..10_000).filter(|&n| is_semiprime(n)).count(), 2_625);
+}
+
+#[test]
+fn test5() {
+    assert_eq!((2..100_000).filter(|&n| is_semiprime(n)).count(), 23_378);
+}
+
+#[test]
+fn test6() {
+    assert_eq!((2..1_000_000).filter(|&n| is_semiprime(n)).count(), 210_035);
+}