C++归并排序示例

/*
 * description:        归并排序示例
 * writeby:            nick
 * date:            2012-10-23 16:35
 *
 */

#include <iostream>
#define maxN 10

using namespace std;

template <class Item>
void merge(Item a[], int l, int m, int r)
{
    int i,j;
    Item tmp[maxN];
    for(i=l; i<=m; i++) tmp[i] = a[i];   //   /
    for(j=m+1; j<=r; j++) tmp[m+1+r-j] = a[j]; 
    i=l; j=r;
    for(int k=l; k<=r; k++)
        a[k] = (tmp[i]<tmp[j])? tmp[i++] : tmp[j--];
}

template <class Item>
void mergesort(Item a[], int l, int r)
{
    if(r <= l) return;
    int m = (r+l) / 2;
    mergesort(a, l, m);
    mergesort(a, m+1, r);
    merge(a, l, m, r);
}

int main()
{
    int a[10] = {0,2,8,1,3,6,4,5,7,9};
    mergesort(a, 0, 9);

    for(int i=0; i<10; i++)
        cout << a[i] << " ";

    return 0;
}