快速排序
``` package algorithm.sort;/**
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快速排序
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思想：类似于归并排序，但是不同于归并排序每次排序寻找一次子数组中点的是，寻找一个更恰当的分区点
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@Author 28370
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@Date 2019-5-13
**/
public class QuickSort {
public static void main(String[] args) {
int[] a= {1,7,4,8,5,3,9,2};
quickSort(a);
for (int i = 0; i < a.length; i++) {
System.out.println(a[i]);}}
public static void quickSort(int[] a){
quickSortInternally(a, 0, a.length-1);
}private static void quickSortInternally(int[] a, int p, int r) {
if(p >= r){
return ;
}
int q = partition(a, p, r);
quickSortInternally(a, p, q-1);
quickSortInternally(a, q+1, r);
}//获取分区点
private static int partition(int[] a, int p, int r) {
int pivot = a[r];
System.out.println(pivot);
int i = p;
for (int j = p; j < r; ++j) {
System.out.println("j="+j+",a[j]="+a[j]);
System.out.println("i="+i+",a[i]="+a[i]);
if(a[j] < pivot){
if(i == j){
++i;
}else{
int temp = a[i];
a[i++] = a[j];
a[j] = temp;
}
}
}
int tmp = a[i];
a[i] = a[r];
a[r] = tmp;
System.out.println("i="+i);
String str ="";
for (int j = 0; j < a.length; j++) {
str+=a[j];
}
System.out.println(str);
return i;
}
}