快速排序的递归和非递归写法

递归：
 

void QuickSort(vector &vec,int low,int high)
{
	int i = low;
	int j = high;

	int tmp = vec[low];
	while (i < j)
	{
		while (i < j&&vec[j] >= tmp)--j;
		vec[i] = vec[j];
		while (i < j&&vec[i] <= tmp)++i;
		vec[j] = vec[i];
	}
	vec[i] = tmp;
	if (i - low - 1 > 0)
	{
		QuickSort(vec, low, i - 1);
	}
	if (high - i - 1 > 0)
	{
		QuickSort(vec, i + 1, high);
	}
}

非递归

void quickSort(vector &vec, int low, int high)
{	
	stack st;
	st.push(low);
	st.push(high);
	while (!st.empty())
	{
		int j= st.top();
		int savehigh = j;
		st.pop();
		int i = st.top();
		int savelow = i;
		st.pop();

		int tmp = vec[i];
		while (i < j)
		{
			while (i < j&&vec[j] >= tmp)--j;
			vec[i] = vec[j];
			while (i < j&&vec[i] <= tmp)++i;
			vec[j] = vec[i];
		}
		vec[i] = tmp;
		if (i - savelow - 1 > 0)
		{
			//QuickSort(vec, low, i - 1);
			st.push(savelow);
			st.push(i - 1);
		}
		if (savehigh - i - 1 > 0)
		{
			//QuickSort(vec, i + 1, high);
			st.push(i + 1);
			st.push(savehigh);
		}
	}
}