From a94e54422a100830dd67d55fe4e8f699d14ffd4d Mon Sep 17 00:00:00 2001
From: mhugent <mhugent@c8812cc2-4d05-0410-92ff-de0c093fc19c>
Date: Tue, 16 Sep 2003 18:21:00 +0000
Subject: [PATCH] made worst case quicksort run nearly impossible by using a
 random element

git-svn-id: http://svn.osgeo.org/qgis/trunk@279 c8812cc2-4d05-0410-92ff-de0c093fc19c
---
 src/qgsattributetable.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/qgsattributetable.cpp b/src/qgsattributetable.cpp
index c876bc36d75..70158e788cd 100644
--- a/src/qgsattributetable.cpp
+++ b/src/qgsattributetable.cpp
@@ -237,6 +237,10 @@ void QgsAttributeTable::qsort(int lower, int upper, int col, bool ascending, boo
     QString v;
     if(upper>lower)
     {
+	//chose a random element (this avoids n^2 worst case)
+	int element=double(rand())/RAND_MAX*(upper-lower)+lower;
+	
+	swapRows(element,upper);
 	v=text(upper,col);
 	i=lower-1;
 	j=upper;