归并排序

#include"aa.h"
#include<vector>
#include<iostream>
#include<numeric>
using namespace std;

void merge(int a[],int left,int mid,int right)
{
	//const int len=sizeof(a);
	int b[10];
	int k;
	for(k=left;k<=right;k++)         //申请新数组b[]将a[]中的值拷贝进去
		b[k]=a[k];
	int i=left,j=mid+1;
	k=left;
	while(i!=mid+1 && j!=right+1)
	{
		if(b[i]<=b[j])
			a[k++]=b[i++];
		else 
			a[k++]=b[j++];		
	}
	while(i<=mid)
		a[k++]=b[i++];
	while(j<=right)
		a[k++]=b[j++];
}

void mergesort(int a[], int left, int right)   //递归调用merge函数
{  
    if (left < right)  
    {  
        int mid = (left + right) / 2;  
        mergesort(a, left, mid);               //左边有序  
        mergesort(a, mid+1,right);            //右边有序  
        merge(a, left, mid, right);        //再将二个有序数列合并  
    }  //if
}

void MergeSort(int a[], int n)              //封装mergesort函数，用户只需提供待排序数组与长度
{   
    mergesort(a, 0, n - 1);       
}  

int main()
{
	int a[10]={5,3,10,7,9,2,4,11,8,1};
	MergeSort(a,10);
	for(int i=0;i<10;i++)
		cout<<a[i]<<' ';
	    cout<<endl;

	system("pause");
	return 0;
}