c++实现二路归并排序的示例代码

void Merger(int *arr, int len, int width)
{
 int *temp =(int *)malloc(sizeof(int) * (len));
 //首先对两路下标分别进行初始化
 int l1 = 0;
 int h1 = l1 + width - 1;
 int l2 = h1 + 1;
 int h2 = l2 + width - 1 < len - 1 ? l2 + width - 1 : len - 1;
 int temppos = 0;
 //判断所在下标位置的值
 while (l1 < len && l2 < len)
 {
 while (l1 <= h1 && l2 <= h2)
 {
  if (arr[l1] < arr[l2])
  {
  temp[temppos++] = arr[l1++];
  }
  else
  {
  temp[temppos++] = arr[l2++];
  }
 }
 //l1有剩余
 while (l1 <= h1)
 {
  temp[temppos++] = arr[l1++];
 }
 //l2有剩余
 while (l2 <= h2)
 {
  temp[temppos++] = arr[l2++];
 }
 //l1 l2向后移动
 l1 = h2 + 1;
 h1 = (l1 + width - 1) < (len - 1) ? (l1 + width - 1) : (len - 1);
 l2 = h1 + 1;
 h2 = (l2 + width - 1) < (len - 1) ? (l2 + width - 1) : (len - 1);
 }
 //奇数归并块 剩下的一个单都块操作
 while (l1 <len)
 {
 temp[temppos++] = arr[l1++];
 }
 //用temp覆盖arr
 for (int i = 0; i < len ; ++i)
 {
 arr[i] = temp[i];
 }
// free(temp);
}
void MergeSort(int *arr, int len)
{
 for (int i = 1; i < len; i *= 2)
 {
 Merger(arr, len, i);
 }
}
void show(int *arr, int len)
{
 for (int i = 0; i < len; ++i)
 {
 cout << arr[i] << " ";
 }
}
int main()
{
 int array[] = { 12, 51, 1, 36, 98, 21, 38, 47 };
 int len = sizeof(array) / sizeof(array[0]);
 MergeSort(array, len);
 show(array, len);
 system("pause");
 return 0;
}

#include<iostream>
using namespace std;
class SortableList
{
public:
	SortableList(int mSize)
	{
		maxSize = mSize;
	  l= new int[maxSize];
		n = 0;
	}
	~SortableList()
	{
		delete[]l;
	}
	void Merge(int, int, int);
	void MergeSort(int,int);
	void Input();
	void Output();
	
   private:
		 int* l;
		 int maxSize;
		 int n;

};
void SortableList::Input()
{
	cout << "请输入要排序的数：";
	for (int i = 0; i <= maxSize - 1; i++)
		cin >> l[i];
}
void SortableList::Output()
{
	cout << "排序后的数是：";
	for (int i = 0; i <= maxSize - 1; i++)
		cout << l[i]<<' ';
}
void SortableList::MergeSort(int left,int right)
{
	if (left < right)//如果序列长度大于1则划分
	{
		int mid = (left + right) / 2;
		MergeSort(left, mid);//对左序列进行排序
		MergeSort(mid + 1, right);//对右序列进行排序
		Merge(left, mid, right);//合并
	}
}
void SortableList::Merge(int left, int mid, int right)
{
	int* temp= new int[right - left + 1];
	int i = left, j = mid + 1, k = 0;
	while ((i <= mid) && (j <= right))//判断序列是否为空
		if (l[i] <= l[j])
			temp[k++] = l[i++];
		else temp[k++] = l[j++];
	while (i <= mid)
		temp[k++] = l[i++];//右序列空了左序列依次写入
	while (j <= right)
		temp[k++] = l[j++];//左序列空了右序列依次写入
	for (i = 0, k = left; k <= right;)
		l[k++] = temp[i++];//临时在数组temp中的排列好的数据放入数组l
}
int main()
{
	int m;
	cout << "请输入要排序的数的数目：";
	cin >> m;
	SortableList a1(m);
	a1.Input();
	a1.MergeSort(0, m-1);
	a1.Output();
}