八大排序-快排

快排是速度最快的排序，時間複雜度爲O(logn),空間複雜度O(logn),不穩定

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void Show(int *arr,int len)
{
	for(int i=0;i<len;i++)
	{
		printf("%d ",arr[i]);
	}
	printf("\n");
}
int Partition1(int *arr,int low,int high)//O(n),O(1) //*******
{
	int tmp = arr[low];//基準
	while(low < high)
	{
		while(low<high && arr[high]>tmp)
		{
			high--;
		}
		arr[low] = arr[high];
		while(low<high && arr[low]<tmp)
		{
			low++;
		}
		arr[high] = arr[low];
	}

	arr[low] = tmp;//low==high
	return low;
}

static void Quick(int*arr,int low,int high)
{
	int par = Partition1(arr,low,high);
	if(low+1 < par)//左邊至少兩個數據
	{
		Quick(arr,low,par-1);
	}
	if(par+1 < high)//右邊至少兩個數據
	{
		Quick(arr,par+1,high);
	}
}

void QuickSort(int *arr,int len)//O(nlogn),O(logn)***,不穩定
{
	Quick(arr,0,len-1);
}

int main()
{
	int arr[] = {4,9,0,12,34,67,8,91,32,54,66,88,2};

	QuickSort(arr,sizeof(arr)/sizeof(arr[0]));
	Show(arr,sizeof(arr)/sizeof(arr[0]));

	return 0;
}