堆排序heapsort

#include<stdio.h>
void swap(int& a,int& b)  
{  
    if(a!=b)  
    {  
        a^=b;  
        b^=a;  
        a^=b;  
    }  
}
void MAX_HEAPIFY(int a[],int length,int i)//a数组第一个存值 
{
    int large=i;
    if(2*i<length && a[i]<a[2*i]){
        large = 2*i;
    }
    if(2*i+1<length && a[large]<a[2*i+1]){
        large = 2*i+1;  
    } 
    if(large!=i){
        swap(a[i],a[large]);
        MAX_HEAPIFY(a,length,large);
    }
}
void BUILD_MAX_HEAP(int a[],int length)//将每个非叶子节点从下向上调用MAX_HEAPIFY 
{
    for(int i = length/2-1;i>=0;i--) 
    {
        MAX_HEAPIFY(a,length,i);
    }
}
void HEAP_SORT(int a[],int length)
{
    BUILD_MAX_HEAP(a,length);
    for(int i = length-1; i>0;i--)
    {
        swap(a[0],a[length-1]);
        MAX_HEAPIFY(a,--length,0);//保证最大堆的性质 
    }

}
int main()
{
    int a[10] = {16,4,10,14,7,9,3,2,8,1};
    HEAP_SORT(a,10);
    for(int i=0;i<10;i++)
    {
        printf("%d ",a[i]);
    }

}