tasks a-s

Task/Permutations/Fortran/permutations-1.f

@@ -0,0 +1,33 @@
+program permutations
+
+  implicit none
+  integer, parameter :: value_min = 1
+  integer, parameter :: value_max = 3
+  integer, parameter :: position_min = value_min
+  integer, parameter :: position_max = value_max
+  integer, dimension (position_min : position_max) :: permutation
+
+  call generate (position_min)
+
+contains
+
+  recursive subroutine generate (position)
+
+    implicit none
+    integer, intent (in) :: position
+    integer :: value
+
+    if (position > position_max) then
+      write (*, *) permutation
+    else
+      do value = value_min, value_max
+        if (.not. any (permutation (: position - 1) == value)) then
+          permutation (position) = value
+          call generate (position + 1)
+        end if
+      end do
+    end if
+
+  end subroutine generate
+
+end program permutations