堆排序(Java版)

public class HeapClass {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] array= {16,14,10,8,7,9,3,2,4,1};
		HeapSort(array);
		for(int i=0;i<array.length;i++) {
			System.out.print(array[i]+" ,");
		}
	}
	public static void Max_Heapify(int[] array,int i,int length) {
		int left=2*i+1;
		int right=2*i+2;
		int largest=i;
		if(left<length&&array[i]<array[left]) {
			largest=left;
		}else
			largest=i;
		if(right<length&&array[largest]<array[right]) 
			largest=right;
		if(largest!=i) {
			int temp=array[largest];
			array[largest]=array[i];
			
			array[i]=temp;
			Max_Heapify(array,largest,length);
		}
	}
	public static void Build_Max_Heap(int[] array) {
		int i;
		for(i=(int)Math.floor((array.length)/2);i>=0;i--) {
			Max_Heapify(array,i,array.length);
		}
	}
	public static void HeapSort(int[] array) {
		Build_Max_Heap(array);
		int i;
		int num=array.length;
		
		for(i=array.length-1;i>=0;i--) {
			int temp=array[0];
			array[0]=array[i];
			array[i]=temp;
			
			Max_Heapify(array,0,i);
		}
	}

}

代码实现基于算法导论中的伪代码,较为关键的是a[0]最后交换完成后,通过length参数控制大顶堆的调整Max_Heapify下标下限。

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转载自blog.csdn.net/God_Mood/article/details/82808241