C++編程歸並排序算法實現示例

void merg_sort(int* a, int fbegin, int fend, int sbegin, int send, int* b)
{
	int L = fbegin;
	int R = sbegin;
	int cursize = fbegin;//z這裡不能重0開始 遞歸後面是按對應開始位置進行賦值的 
	while (L <= fend && R <= send)
	{
		if (a[L] > a[R])
		{
			b[cursize++] = a[R++];
		}
		else
		{
			b[cursize++] = a[L++];
		}
	}
	while (L <= fend)
	{
		b[cursize++] = a[L++];
	}
	while (R <= send)
	{
		b[cursize++] = a[R++];
	}
	memcpy(a+fbegin, b+fbegin, sizeof(int) * (send-fbegin+1));
  //要開始位置進行賦值不然後面遞歸會造成重復對同一個地方賦值 
}

void Merg_sort(int* a, int left, int right, int* b)
{
 	int min = (left + right) / 2;
	if (left < right) 
	{
		Merg_sort(a, left, min, b);//將左邊的分開
		Merg_sort(a, min + 1, right, b);//將右邊的分開
		merg_sort(a, left, min, min + 1, right, b);//逆過程 先分開後排序 後分開的先排序 
	}
}

int main()
{
 	int a[10] = { 1,3,4,9,9,2,4,15,17,10 };
	int b[10];
	Merg_sort(a, 0, 9, b);
	for (int i = 0; i < 10; i++)
	{
		printf("%d\t", a[i]);
	}
	return 0;
}