堆排序学习

package com.company.排序;

import java.util.Arrays;

public class 堆排序test {

	public static void main(String[] args) {
		int a[]=new int[]{1,3,6,9,14,0,89,4,5};
		heapSort(a);
		System.out.println(Arrays.toString(a));
	}
	public static void heapSort(int[] arr) {
		if(arr==null||arr.length<2){
			return;
		}
		//构建大顶堆 不停的往堆中放 
		for(int i=0;i0){
			swap(arr, 0, --heapSize);
			heapify(arr,0,heapSize);
		}

	}
	private static void heapInsert(int[] arr, int index){ //向堆内增加值
		while(arr[index] > arr[(index - 1) / 2]) {
			swap(arr, index, (index-1) /2);
			index = (index -1)/2;
		}
	}

	private static void heapify(int[] arr, int index, int size){   //大顶堆化
		int left = 2*index+1;
		while(left < size){
			int largest = left+1 arr[left] ? left+1 : left;
			largest = arr[largest] > arr[index] ? largest: index;
			if(largest==index){
				return;
			}
			swap(arr,index, largest);
			index=largest;
			left = largest * 2 +1;
		}
	}
	private static void swap(int arr[], int x, int y){ //交换两个数
		int temp = arr[x];
		arr[x] = arr[y];
		arr[y] = temp;
	}
}