LazStats: Add QuickSort routine.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7696 8e941d3f-bd1b-0410-a28a-d453659cc2b4

applications/lazstats/source/units/utils.pas

@@ -28,13 +28,15 @@ procedure Exchange(var a, b: String); overload;
 procedure SortOnX(X: DblDyneVec; Y: DblDyneVec = nil; Z: DblDyneVec = nil);
 procedure SortOnX(X: DblDyneVec; Y: DblDyneMat);
 
+procedure QuickSortOnX(X: DblDyneVec; Y: DblDyneVec = nil; Z: DblDyneVec = nil);
+
 function IndexOfString(L: StrDyneVec; s: String): Integer;
 
 
 implementation
 
 uses
-  ToolWin;
+  Math, ToolWin;
 
 // https://stackoverflow.com/questions/4093595/create-ttoolbutton-runtime
 procedure AddButtonToToolbar(AToolButton: TToolButton; AToolBar: TToolBar);
@@ -179,6 +181,50 @@ begin
   end;
 end;
 
+procedure QuickSortOnX(X: DblDyneVec; Y: DblDyneVec = nil; Z: DblDyneVec = nil);
+
+  procedure DoQuickSort(L, R: Integer);
+  var
+    I,J: Integer;
+    P: Integer;
+  begin
+    repeat
+      I := L;
+      J := R;
+      P := (L+R) div 2;
+      repeat
+        while CompareValue(X[P], X[I]) > 0 do inc(I);
+        while CompareValue(X[P], X[J]) < 0 do dec(J);
+        if I <= J then begin
+          if I <> J then begin
+            Exchange(X[I], X[J]);
+            if Y <> nil then
+              Exchange(Y[I], Y[J]);
+            if Z <> nil then
+              Exchange(Z[I], Z[J]);
+          end;
+
+          if P = I then
+            P := J
+          else if P = J then
+            P := I;
+
+          inc(I);
+          dec(J);
+        end;
+      until I > J;
+
+      if L < J then
+        DoQuickSort(L, J);
+
+      L := I;
+    until I >= R;
+  end;
+
+begin
+  DoQuickSort(0, High(X));
+end;
+
 function IndexOfString(L: StrDyneVec; s: String): Integer;
 var
   i: Integer;