归并排序

#include<iostream>
using namespace std;
const int maxn=100;
void merge(int a[],int l1,int r1,int l2,int r2)
{
	int i=l1;
	int j=l2;
	int temp[maxn];
	int index=0;
	while(i<=r1&&j<=r2)
	{
		if(a[i]<=a[j])
		{
			temp[index++]=a[i++];
		}
		else
		{
			temp[index++]=a[j++];
		}
	}
	while(i<=r1) temp[index++]=a[i++];
	while(j<=r2) temp[index++]=a[j++];
	for(int i=0;i<index;i++)
	{
		a[l1+i]=temp[i];
	}
}
void mergesort(int a[],int left,int right)
{
	if(left<right)
	{
		int mid=(left+right)/2;
		mergesort(a,left,mid);
		mergesort(a,mid+1,right);
		merge(a,left,mid,mid+1,right);
	}
}
int main()
{
	int a[7]={12,33,57,66,18,27,64};
	mergesort(a,0,6);
	for(int i=0;i<7;i++)
	{
		cout<<a[i]<<endl;
	}
	system("pause");
	return 0;
}