(!******************************************************
   Mosel User Guide Example Problems
   ================================= 

   file qsort1.mos 
   ``````````````` 
   'forward' definition of subroutines.
 
   (c) 2008 Fair Isaac Corporation
       author: Y. Colombani, 2001
*******************************************************!)

model "Quick sort 1"

 parameters
  LIM=50
 end-parameters

 forward procedure qsort_start(L:array(range) of integer)

 declarations
  T:array(1..LIM) of integer
 end-declarations

 forall(i in 1..LIM) T(i):=round(.5+random*LIM)
 writeln(T)
 qsort_start(T)
 writeln(T)
 
 
! Swap the positions of two numbers in an array
 procedure swap(L:array(range) of integer,i,j:integer)
  k:=L(i)
  L(i):=L(j)
  L(j):=k
 end-procedure


! Main sorting routine
 procedure qsort(L:array(range) of integer,s,e:integer)
  v:=L((s+e) div 2)              ! Determine a partitioning value
  i:=s; j:=e
  repeat                         ! Partition the array into two subarrays
   while(L(i)<v) i+=1
   while(L(j)>v) j-=1
   if i<j  then
    swap(L,i,j)
    i+=1; j-=1
   end-if
  until i>=j
                                 ! Recursively sort the two subarrays
  if j<e and s<j then qsort(L,s,j); end-if
  if i>s and i<e then qsort(L,i,e); end-if
 end-procedure


! Start of the sorting process
 procedure qsort_start(L:array(r:range) of integer)
  qsort(L,getfirst(r),getlast(r))
 end-procedure

end-model