面试常见的排序

import java.util.Arrays;

public class SortTest {

	public static void main(String[] args) {
		int[] a = {11,1,3,5,9,7,8,2,4,6,0,10};
//		quickSort(a,0,a.length-1);
		heapSort(a);
		System.out.println(Arrays.toString(a));
	}
	public static void helpExch(int[] a,int i,int j){
		int temp = a[i];
		a[i] = a[j];
		a[j] = temp;
	}
	//Bubble Sort冒泡排序
	public static void bubbleSort(int[] a){
		for(int i=0;i<a.length;i++){
			for(int j=0;j<a.length-1;j++){
				if(a[j]>a[j+1]){
					helpExch(a,j,j+1);
				}
			}
		}
	}
	
	//Quicksort 快速排序
	public static void quickSort(int[] a,int s,int e){
		if(s>=e) return; 
		int i = s;
		int j = e;
		int temp = a[j];
		while(i<j){
			while (i<j&&a[i]<temp) i++;
			while (i<j&&a[j]>=temp) j--;
			if(i<j) helpExch(a,i,j);
		}
		helpExch(a,e,j);
		quickSort(a,s,j-1);
		quickSort(a,j+1,e);
	}
	
	//Heapsort 堆排序
	
	//堆排序
	public static void heapSort(int[] a){
		buildMaxHeap(a);
		for(int i=a.length-1;i>0;i--){
			helpExch(a, 0, i);
			maxHeap(a,i,0);
		}
	}
	
	//最大堆调整
	private static void maxHeap(int[] a, int heapSize, int index) {
		int left = 2*index + 1;
		int right = 2*index +2;
		int max = index;
		if(left<heapSize&&a[max]<a[left]) max = left;
		if(right<heapSize&&a[max]<a[right]) max = right;
		if(max!=index){
			helpExch(a, index, max);
			maxHeap(a,heapSize,max);
		}
		
	}
	
	//建立最大堆
	private static void buildMaxHeap(int[] a) {
		for(int i=a.length/2;i>0;i--){
			maxHeap(a,a.length,i);
		}
		
	}
	
}