堆排序

//折半插入排序
#include<iostream>
using namespace std;
void swap(int a[], int i, int j){  //交换
int c = a[i];
a[i] = a[j];
a[j] = c;
}
void adjustDown(int a[], int k, int len){//大顶堆，向下调整，小的下沉到底
a[0] = a[k];
for (int i = 2*k; i <= len; i = i * 2){
if (i < len&&a[i + 1]>a[i])
i++;
if (a[k] < a[i]){
swap(a,i,k);
k = i;
}
}
}
void buildMaxHeap(int a[], int len){ //a[]是从1开始
for (int i = len / 2; i > 0; i--){
adjustDown(a, i, len);
}

}
void dsort(int a[], int len){
buildMaxHeap(a, 9);
for (int i=9; i > 1; i--){
swap(a, 1, i);
adjustDown(a, 1, i-1);
}
for (int i = 1; i <= len; i++)
cout << a[i] << endl;
}
int main(){
int a[] = { 0, 9,8,7,6,5,4,3,2,1 };
dsort(a, 9);
}