find_next_comb Subroutine

    pure subroutine find_next_comb(comb, k, n, finish)

        integer, intent(in) :: k, n
        integer, intent(inout) :: comb(k)
        logical, intent(out) :: finish
        integer :: i

        if(k == 0 .or. n == 0) then
            finish = .true.
            return
        else if(comb(1) > n - k) then
            finish = .true.
            return
        else
            finish = .false.
        end if

        i = k
        comb(i) = comb(i) + 1

        do
            if(i < 1 .or. comb(i) < n - k + i + 1) exit
            i = i - 1
            comb(i) = comb(i) + 1
        end do

        do i = i + 1, k
            comb(i) = comb(i - 1) + 1
        end do

    end subroutine find_next_comb