Sel_sort

note
    description: "Summary description for {SELECTION_SORT}."
    author: ""
    date: "$Date$"
    revision: "$Revision$"

class
    SELECTION_SORT



feature
index_of_min(ar: ARRAY [INTEGER]; lower: INTEGER):INTEGER
        --find index of smallest element in ar in the range of lower and the max index.
        require
            lower_positiv : lower >=1
            lower_in_range: lower <= ar.count
            ar_not_void: ar/= Void
        local
                i, min, index: INTEGER
        do
                from
                        i:=lower
                        min := ar.item (i)
                        index := i
                until
                        i+1 > ar.count
                loop
                        if  ar.item(i+1) < min then
                                min := ar.item(i+1)
                                index := i+1
                        end
                        i := i + 1
                end
                 Result := index
        ensure
            result_is_set: Result /= Void
        end


selectionsort (ar: ARRAY [INTEGER]):ARRAY[INTEGER]
                -- sort Array x with selectionsort
        require
            ar_not_void: ar/=VOID
        local
            i: INTEGER
            min_index: INTEGER
            ith: INTEGER
        do
            from
                i:=1
            until
                i= ar.count
            loop
                min_index := index_of_min(ar,i)
                ith:=ar[i]
                ar[i]:= ar[min_index]
                ar[min_index]:=ith
                i:= i+1
            end
            Result:= ar
        ensure
            Result_is_set: Result /= Void
        end
end