快速排序

最简单的快排。

以头元素作为标记元素，将大于标记元素的数字放在其的右边，小于的放在其左边。之后对于左边和右边的分别排序。

parttitioned (input list[], input left, input right)
	pivot <- list[left]
	i <- left
	j <- right
	while (i < j) do
		whlie (i < j and list[j] >= pivot) do
			j <- j - 1
		end
		if (i < j)
			list[i] <- list [j]
		
		whlie (i < j and list[i] < pivot) do
			i <- i + 1
		end
		if (i < j)
			list[j] <- list [i]
	end
	list[i] <- pivot
	return i

quicksort (input list[], input left, input right)
	if (left < right)
		mid = parttitioned(list, left, left)
		quicksort (list, left, mid-1)
		quicksort (list, mid+1, right)
	end if

c/c++

int partitionsed (int a[], int left, int right)
{
	int pivot = a[left];
	int i = left,j = right;
	int k;
	while (i < j)
	{
		while (i < j && a[j] >= pivot)
			j--;
		if (i < j)
			a[i] = a[j];
		while (i < j && a[i] < pivot)
			i++;
		if (i < j)
			a[j] = a[i];	
	}
	a[i] = pivot;
        return i;
}

void quicksort(int a[],int left,int right)
{
	if (left < right)
	{
		int insert = partitionsed(a,left,right);
		quicksort (a,left,insert-1);
		quicksort (a,insert+1, right);
	}
}

 python

def partitioned(list, left, right):
    pivot = list[left]
    i = left
    j = right
    while i < j:
        while i < j and list[j] >= pivot:
            j = j - 1
        if i < j:
            list[i] = list[j]
        while i < j and list[i] < pivot:
            i = i + 1
        if i < j:
            list[j] = list[i]
        list[i] = pivot
    return i
def QuickSort(list, left, right):
    if (left < right ):
        mid = partitioned(list, left, right)
        QuickSort(list, left, mid-1)
        QuickSort(list, mid+1,right)

list = [5, 1, 7, 3, 7, 0, 4, 8, 6, 9]
QuickSort(list, 0, 9)
print list