C#快速排序算法实例分析

public static int[] QuickSort(int[] arr)
{
 if (arr.Length <= 1)
 return arr;
 int pivot = arr.Length - 1;
 int[] less = GetLessThanEqualToPivot(arr, pivot);
 int[] greater = GetGreaterThanPivot(arr, pivot);
 return Concatenate(QuickSort(less),arr[pivot],QuickSort(greater));
}
public static int[] Concatenate(int[] less,int pivotElement,int[] greater)
{
 List<int> _result = new List<int>();
 _result.AddRange(less);
 _result.Add(pivotElement);
 _result.AddRange(greater);
 return _result.ToArray();
}
public static int[] GetLessThanEqualToPivot(int[] arr, int pivot)
{
 List<int> _result = new List<int>();
 for (int i = 0; i < arr.Length - 1; i++)
 {
 if (arr[i] <= arr[pivot])
 {
  _result.Add(arr[i]);
 }
 }
 return _result.ToArray();
}
public static int[] GetGreaterThanPivot(int[] arr, int pivot)
{
 List<int> _result = new List<int>();
 for (int i = 0; i < arr.Length - 1; i++)
 {
 if (arr[i] > arr[pivot])
 {
  _result.Add(arr[i]);
 }
 }
 return _result.ToArray();
}