Initial data commit

Task/Sorting-algorithms-Counting-sort/Fortran/sorting-algorithms-counting-sort-1.f

@@ -0,0 +1,43 @@
+module CountingSort
+  implicit none
+
+  interface counting_sort
+     module procedure counting_sort_mm, counting_sort_a
+  end interface
+
+contains
+
+  subroutine counting_sort_a(array)
+    integer, dimension(:), intent(inout) :: array
+
+    call counting_sort_mm(array, minval(array), maxval(array))
+
+  end subroutine counting_sort_a
+
+  subroutine counting_sort_mm(array, tmin, tmax)
+    integer, dimension(:), intent(inout) :: array
+    integer, intent(in) :: tmin, tmax
+
+    integer, dimension(tmin:tmax) :: cnt
+    integer :: i, z
+
+    cnt = 0                   ! Initialize to zero to prevent false counts
+    FORALL (I=1:size(array))  ! Not sure that this gives any benefit over a DO loop.
+        cnt(array(i)) = cnt(array(i))+1
+    END FORALL
+!
+!   ok - cnt contains the frequency of every value
+!   let's unwind them into the original array
+!
+    z = 1
+    do i = tmin, tmax
+       do while ( cnt(i) > 0 )
+          array(z) = i
+          z = z + 1
+          cnt(i) = cnt(i) - 1
+       end do
+    end do
+
+  end subroutine counting_sort_mm
+
+end module CountingSort

Task/Sorting-algorithms-Counting-sort/Fortran/sorting-algorithms-counting-sort-2.f

@@ -0,0 +1,17 @@
+program test
+  use CountingSort
+  implicit none
+
+  integer, parameter :: n = 100, max_age = 140
+
+  real, dimension(n) :: t
+  integer, dimension(n) :: ages
+
+  call random_number(t)
+  ages = floor(t * max_age)
+
+  call counting_sort(ages, 0, max_age)
+
+  write(*,'(I4)') ages
+
+end program test