PROGRAM Gen_Selection_Sort

! This program implements Selection Sort on a run-time array.

IMPLICIT NONE

INTEGER :: I, Smallest_Location, Lower_Ind_A, Upper_Ind_A

REAL, DIMENSION(:), ALLOCATABLE :: A

REAL, DIMENSION(1) :: Loc_Array

REAL :: Smallest

! Now read the lower and upper indices of array A.

PRINT *, "Enter lower and upper indices of A:"

READ *, Lower_Ind_A, Upper_Ind_A

! Now allocate memory for array A:

ALLOCATE(A(Lower_Ind_A:Upper_Ind_A))

! Now read elements of A.

PRINT *, "Enter elements of A. Notice that &

&there are ", Upper_Ind_A-Lower_Ind_A+1, " of them."

READ *, A

! Now we start the sorting process.

! =======================

! Selection Sort starts here.

DO I=Lower_Ind_A, Upper_Ind_A-1

! First we find the minimum value in the subarray A(I:Upper_Ind_A).

Smallest=MINVAL(A(I:Upper_Ind_A))

! Now we find the location of the first occurance of the

! minimum value with respect to the subarray A(I:Upper_Ind_A).

! Notice that the function MINLOC returns a

! one-dimensional array.

Loc_Array=MINLOC(A(I:Upper_Ind_A))

! Now we find the location of the first occurance of the

! minimum value with respect to the array A.

Smallest_Location=Loc_Array(1)+I-1

! Now swap the element whose index is I with the

! smallest element.

A(Smallest_Location)=A(I)

A(I)=Smallest

END DO

! Selection Sort Ends here.

!=====================

! Now we print the sorted array:

PRINT *, A

! Now free memory allocated for A.

! Notice that since Loc_Array is a compile-time array,

! then you canNOT include a statement like DEALLOCATE(Loc_Array).

! You use DEALLOCATE and ALLOCATE only for run-time arrays.

DEALLOCATE(A)

END PROGRAM Gen_Selection_Sort