Sorting algorithms/Quicksort: Difference between revisions

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@@ Line 7,292: / Line 7,292: @@
 =={{header|Pascal}}==
+{{works with|FPC}}
 <syntaxhighlight lang="pascal">
+program QSortDemo;
-{ X is array of LongInt }
-Procedure QuickSort ( Left, Right : LongInt );
+{$mode objfpc}{$h+}{$b-}
-Var
-  i, j,
+procedure QuickSort(var A: array of Integer);
-  tmp, pivot : LongInt;         { tmp & pivot are the same type as the elements of array }
+  procedure QSort(L, R: Integer);
-Begin
+  var
-  i:=Left;
+    I, J, Tmp, Pivot: Integer;
-  j:=Right;
+  begin
-  pivot := X[(Left + Right) shr 1]; // pivot := X[(Left + Right) div 2]
+    if R - L < 1 then exit;
-  Repeat
-    While pivot > X[i] Do inc(i);   // i:=i+1;
+    I := L; J := R;
+    {$push}{$q-}{$r-}Pivot := A[(L + R) shr 1];{$pop}
-    While pivot < X[j] Do dec(j);   // j:=j-1;
+    repeat
-    If i<=j Then Begin
-      tmp:=X[i];
+      while A[I] < Pivot do Inc(I);
-      X[i]:=X[j];
+      while A[J] > Pivot do Dec(J);
-      X[j]:=tmp;
+      if I <= J then begin
-      dec(j);   // j:=j-1;
+        Tmp := A[I];
-      inc(i);   // i:=i+1;
+        A[I] := A[J];
-    End;
+        A[J] := Tmp;
+        Inc(I); Dec(J);
-  Until i>j;
+      end;
-  If Left<j Then QuickSort(Left,j);
+    until I > J;
-  If i<Right Then QuickSort(i,Right);
+    QSort(L, J);
-End;
+    QSort(I, R);
+  end;
+begin
+  QSort(0, High(A));
+end;
+procedure PrintArray(const A: array of Integer);
+var
+  I: Integer;
+begin
+  Write('[');
+  for I := 0 to High(A) do
+    if I < High(A) then Write(A[I], ', ')
+    else Write(A[I]);
+  WriteLn(']');
+end;
+var
+  a: array[-7..6] of Integer = (-34, -20, 30, 13, 36, -10, 5, -25, 9, 19, 35, -50, 29, 11);
+begin
+  QuickSort(a);
+  PrintArray(a);
+end.
 </syntaxhighlight>
+{{out}}
+<pre>
+[-50, -34, -25, -20, -10, 5, 9, 11, 13, 19, 29, 30, 35, 36]
+</pre>
 =={{header|Perl}}==