归并排序的一点见解

归并排序

void Merge(int a[],int term[],int first,int last)
{
	int mid = (first+last)>>1;
	int i = first;
	int j = mid + 1;
	int k = 0;
	while(i<=mid&&j<=last)
	{
		if(a[i]<=a[j])
			term[k++] = a[i++];
		else
			term[k++] = a[j++];
	}
	while(i<=mid)
		term[k++] = a[i++];
	while(j<=last)
		term[k++] = a[j++];

	for(int i=0;i<k;i++)
	{
		a[first+i] = term[i];
	}
}

void Mergesort(int a[],int term[],int first,int last)
{
	int mid = (first+ last)>>1;
	if(first<last)
	{
		Mergesort(a,term,first,mid);
		Mergesort(a,term,mid+1,last);
		Merge(a,term,first,last);
	}

}

bool mergesort(int a[],int n)
{
	int *p = new int[n];
	if(p==NULL)
		return false;
	Mergesort(a,p,0,n-1);
	delete []p;
	return true;
}