Data update

Task/Additive-primes/Fortran/additive-primes.f

@@ -0,0 +1,66 @@
+program AdditivePrimes
+      implicit none
+
+      integer :: i, j, digit_sum, count
+      logical :: is_prime
+
+      ! Arrays to track prime numbers and additive primes
+      logical, dimension(500) :: prime_check
+      logical, dimension(500) :: additive_prime_check
+
+      ! Initialize arrays
+      prime_check = .true.
+      prime_check(1) = .false.
+      additive_prime_check = .false.
+
+      ! Sieve of Eratosthenes to find primes
+      do i = 2, int(sqrt(real(500)))
+        if (prime_check(i)) then
+          do j = i*i, 500, i
+            prime_check(j) = .false.
+          end do
+        end if
+      end do
+
+      ! Find additive primes
+      count = 0
+      do i = 2, 500
+        if (prime_check(i)) then
+          ! Calculate digit sum
+          digit_sum = sum_digits(i)
+
+          ! Check if digit sum is also prime
+          if (prime_check(digit_sum)) then
+            additive_prime_check(i) = .true.
+            count = count + 1
+          end if
+        end if
+      end do
+
+      ! Print results
+      print *, "Additive Primes less than 500:"
+      do i = 2, 500
+        if (additive_prime_check(i)) then
+          print *, i
+        end if
+      end do
+
+      print *, "Total number of additive primes:", count
+
+      contains
+
+      ! Function to calculate sum of digits
+      function sum_digits(num) result(total)
+        integer, intent(in) :: num
+        integer :: total, temp_num
+
+        total = 0
+        temp_num = num
+
+        do while (temp_num > 0)
+          total = total + mod(temp_num, 10)
+          temp_num = temp_num / 10
+        end do
+      end function sum_digits
+
+      end program AdditivePrimes

Task/Additive-primes/Langur/additive-primes.langur

@@ -1,15 +1,15 @@
 val isPrime = fn(i) {
 	i == 2 or i > 2 and
-		not any(fn x: i div x, pseries(2 .. i ^/ 2))
+		not any(series(2 .. i ^/ 2, asconly=true), by=fn x:i div x)
 }
 
-val sumDigits = fn i: fold(fn{+}, s2n(string(i)))
+val sumDigits = fn i: fold(s2n(string(i)), by=fn{+})
 
 writeln "Additive primes less than 500:"
 
 var cnt = 0
 
-for i in [2] ~ series(3..500, 2) {
+for i in [2] ~ series(3..500, inc=2) {
     if isPrime(i) and isPrime(sumDigits(i)) {
         write "{{i:3}}  "
         cnt += 1

Task/Additive-primes/Scala/additive-primes.scala

@@ -0,0 +1,26 @@
+def isPrime(n: Int): Boolean = {
+  @annotation.tailrec
+  def checkDivisor(d: Int): Boolean = {
+    if (d * d > n) true
+    else if (n % d == 0) false
+    else checkDivisor(d + 2)
+  }
+
+  if (n < 2) false
+  else if (n == 2 || n == 3) true
+  else if (n % 2 == 0 || n % 3 == 0) false
+  else checkDivisor(5)
+}
+
+private def digitSum(n: Int): Int = n.toString.map(_ - '0').sum
+
+private def additivePrime(n: Int): Boolean = isPrime(n) && isPrime(digitSum(n))
+
+private def testAdditivePrime(max: Int): Unit = {
+  val result = (2 to max).filter(additivePrime)
+  println(result.mkString(", "))
+  println(s"Found ${result.length} additive primes less than 500.")
+}
+
+@main def main(): Unit =
+  testAdditivePrime(500)