c_cpp 快速排序

Posted 2021-05-14

class QuickSort {
public:
int quicksort(int *A,int left, int right)
{
	if (left < right)
	{
		int mid = (left + right) / 2;
		int key = A[mid];//存放中间值
		vector<int> B(right-left+1);
		int j = 0; int k = right - left;
		for (int i = left; i <= right; i++)  //根据key值进行左右分组
		{
			if (A[i] < key)
			{
				B[j++] = A[i];
			}
			else if (A[i] >= key)
			{
				if (i != mid)
				{
					B[k--] = A[i];
				}
				else
				{
					continue;
				}
			}
		}
		B[j] = key;
		for (int i = left; i <= right; i++)
		{
			A[i] = B[i - left];
			cout << A[i] << " ";
		}
		cout << endl;
		//j每次都是从零开始的，不是枢纽值
		return j+left;
	}
	//这里因为有个if判断，若不满足if那么就会跳过这个代码没有返回值，所以需要一个return
	return 0;
}
void merge(int *A,int left, int right)
{
	if (left < right)
	{	
		int center = quicksort(A,left, right);
		merge(A, left, center-1);
		merge(A, center + 1, right);
	}	
}

void mergeSort(int* A, int n)
{
	// write code here
	merge(A, 0, n-1);
}
}