快速排序算法是最快的排序算法，當然它是針對大量通常無序的集合而言是正確的。

public?void?QSort()

{

????RecQSort(0,?numElements?-?1);

}

public?void?RecQSort(int?first,?int?last)

{

????if?((last?-?first)?<=?0)

????????return;

????else

????{

????????int?part?=?this.Partition(first,?last);

????????RecQSort(first,?part?-?1);

????????RecQSort(part?+?1,?last);

????}

}

public?int?Partition(int?first,?int?last)

{

????int?pivotVal?=?arr[first];

????int?theFirst?=?first;

????bool?okSide;

????first++;

????do

????{

????????okSide?=?true;

????????while?(okSide)

????????????if?(arr[first]?>?pivotVal)

????????????????okSide?=?false;

????????????else

????????????{

????????????????first++;

????????????????okSide?=?(first?<=?last);

????????????}

????????okSide?=?true;

????????while?(okSide)

????????????if?(arr[last]?<=?pivotVal)

????????????????okSide?=?false;

????????????else

????????????{

????????????????last--;

????????????????okSide?=?(first?<=?last);

????????????}

????????if?(first?<?last)

????????{

????????????Swap(first,?last);

????????????this.DisplayElements();

????????????first++;

????????????last--;

????????}

????}?while?(first?<=?last);

????Swap(theFirst,?last);

????this.DisplayElements();

????return?last;

}

public?void?Swap(int?item1,?int?item2)

{

????int?temp?=?arr[item1];

????arr[item1]?=?arr[item2];

????arr[item2]?=?temp;

}

如果數組內的的數據是隨機的，那么選擇第一個

最流行的選擇中間值得方法。

theFirst?=?arr[(int)arr.GetUpperBound(0)?/?2]

快速排序算法