大顶堆，小顶堆代码实现

只贴出代码参考，原理百度有很多讲解

大顶堆

public class LargeHeap {

    public static  void sort(Comparable[] a){
        for (int i = a.length/2-1; i >=0 ; i--) {
            adjustHeap(a,i,a.length-1);
        }
        建堆后 a[0]为最大值
        for (int i = a.length-1; i >0;i--) {
            //每次将堆顶和最后一个元素交换
            exch(a,0,i);
           //算法平均性能 nlogn
            //依次建堆n是for循环一层 logn 每次调整大顶堆 a[0]下沉 每次只比较交换 <logn
            adjustHeap(a,0,i-1);
        }
    }
    /*
    * 每次将数组lo...hi调整为大顶堆
    *
    * */
    public  static void adjustHeap(Comparable[] a,int lo,int hi){
         Comparable val=a[lo];
        //此处代码不难立即自己手动画图验证即可
        for (int i = lo*2+1; i <=hi ; i*=2) {
            if(i<hi&&less(a[i],a[i+1])) i++;
            if(!(less(val,a[i]))) break;
            a[lo]=a[i];lo=i;
        }
        a[lo]=val;
    }

    private  static  boolean less(Comparable v,Comparable w){
        return v.compareTo(w)<0;
    }

    private  static  void exch(Comparable[] a,int i,int j){
        Comparable t=a[i];a[i]=a[j];a[j]=t;
    }
    public  static boolean isSorted(Comparable[] a){
        for (int i = 0; i <a.length ; i++) {
            if(less(a[i],a[i])) return false;
        }
        return  true;
    }
    public  static  void main(String[] args){
        Comparable a[]={5,643,-1,53,4,1,2,97,88,9,0};
        sort(a);
        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
        }
    }
}

小顶堆

public class LittleHeap {
    public static  void sort(Comparable[] a){
        for (int i = a.length/2-1; i >=0 ; i--) {
            adjustHeap(a,i,a.length-1);
        }
        for (int i = a.length-1; i >0; i--) {
            exch(a,0,i);
            adjustHeap(a,0,i-1);
        }
    }
    /*
    * 每次将数组lo...hi调整为小顶堆 用到的方法是 堆的上浮算法
    *
    * */
    public  static void adjustHeap(Comparable[] a,int lo,int hi){
        Comparable val=a[lo];
        for (int i = lo*2+1; i <=hi ; i*=2) {
------------------------------这段代码是不同的-------------------------
---------------------------------------------------------------------
            /*检查边界 i=hi-1时候保证i+1 存在 */
            if(i<hi&&less(a[i+1],a[i])) i++;
            /*如果不经过上一步就直接和当前节点子节点比对（此时只有一个节点）*/
            if(less(a[i],val)){
                a[lo]=a[i];lo=i;
            }else break;
--------------------------------------------------------------------------
        }
        a[lo]=val;
    }

    private  static  boolean less(Comparable v,Comparable w){
        return v.compareTo(w)<0;
    }
    private  static  void exch(Comparable[] a,int i,int j){
        Comparable t=a[i];a[i]=a[j];a[j]=t;
    }
    public  static boolean isSorted(Comparable[] a){
        for (int i = 0; i <a.length ; i++) {
            if(less(a[i],a[i])) return false;
        }
        return  true;
    }
    public  static  void main(String[] args){
        Comparable a[]={5,643,53,4,1,2,97,88,9,0};
        sort(a);
        for (int i = a.length-1; i >=0; i--) {
            System.out.println(a[i]);
        }
    }



}