归并排序

#include<iostream>
using namespace std;


void sort(int a[],int first,int mid,int last,int temp[])
{
	int i=first;
	int j=mid;
	int count=0;
	while(1)
	{
		if(a[i]<a[j])
		{
			temp[count++]=a[i++];
		}
		else
		{
			temp[count++]=a[j++];
		}
		if(i==mid)
		{
			while(j<last)
				temp[count++]=a[j++];
			break;
		}
		if(j==last)
		{
			while(i<mid)
				temp[count++]=a[i];
			break;
		}
	}
	for(int k=0;k<count;k++)
	{
		a[first+k]=temp[k];
	}

}
void merge(int a[],int first,int last,int temp[])
{
	if(last>first)
	{
		int mid=(first+last)/2;
		merge(a,first,mid,temp);
		merge(a,mid+1,last,temp);
		sort(a,first,mid,last,temp);
	}

}
void main()
{
	
	int a[]={1,4,7,9,12,2,5,9,11,13};
	int last=sizeof(a)/sizeof(int);
	int* p =new int[last]();
	merge(a,0,last,p);
	for(int i=0;i<last;i++)
	{
		cout<<a[i]<<endl;
	}
}