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Sortera arrayer på olika sätt
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Kategori: Strangar
Inlagt: 2004-06-10
Läst: 1461
Inlagt av: Staffan Berg
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Beskrivning |
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Exempel på olika sorteringsordningar av en array.
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Kod |
unit QSort;
interface
type CompFunc = function(Item1, Item2 : word) : integer;
procedure QuickSort(
var Data;
//An array. Must be [0..Count-1] and not [1..Count] or anything else!
Count,
//Number of elements in the array
Size : word;
//Size in bytes of a single element -- e.g. 2 for integers or words,
4 for longints, 256 for string s and so on
Compare : CompFunc);
//The function that decides which element is "greater" or "less". //Must return an integer that's < 0 if the first element is less, 0 if they're
//equal and > 0 if the first element is greater. A simple Compare for words can look like this:
function WordCompare(Item1, Item2: word): integer;
begin
WordCompare := MyArray[Item1] - MyArray[Item2]
end;
implementation
procedure QuickSort;
procedure Swap(Item1, Item2 : word);
var P1, P2 : ^byte; I : word;
begin
if Item1 <> Item2 then
begin
I := Size;
P1 := @Data; inc(P1, Item1 * Size);
P2 := @Data; inc(P2, Item2 * Size);
asm
mov cx,I { Size }
les di,P1
push ds
lds si,P2
@L:
mov ah,es:[di]
lodsb
mov [si-1],ah
stosb
loop @L
pop ds
end
end
end;
procedure Sort(Left, Right: integer);
var i, j, x, y : integer;
begin
i := Left; j := Right; x := (Left+Right) div 2;
repeat
while compare(i, x) < 0 do inc(i);
while compare(x, j) < 0 do dec(j);
if i <= j then
begin
swap(i, j); inc(i); dec(j)
end
until i > j;
if Left < j then Sort(Left, j);
if i < Right then Sort(i, Right)
end;
begin Sort(0, Count) end;
end. //of unit
//A simple testprogram can look like this:
program QS_Test; //Test QuickSort la C
uses qsort;
var v: array[0..9999] of word;
i: word;
{$F+} //Must be compiled as FAR calls!
function cmpr(a, b: word): integer;
begin cmpr := v[a] - v[b] end;
function cmpr2(a, b: word): integer;
begin cmpr2 := v[b] - v[a] end;
{$F-}
begin
randomize;
for i := 0 to 9999 do v[i] := random(20000);
quicksort(v, 10000, 2, cmpr); //in order lo to hi
quicksort(v, 10000, 2, cmpr2); //we now have a sorted list, sort it in
//reverse -- nasty for qsort!
quicksort(v, 10000, 2, cmpr); //and reverse again
quicksort(v, 10000, 2, cmpr); //sort a sorted list -- also not very popular
end.
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