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Copy pathThreeQuickSort.java
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47 lines (45 loc) · 1.46 KB
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package sort;
import java.util.Arrays;
import java.util.Random;
/*
* 三路随机基准快速排序
*
* */
public class ThreeQuickSort {
public static void main(String[] args) {
int a[]={1,0,0,0,2,2};
new ThreeQuickSort().swapNums(a,0,5);
System.out.println(Arrays.toString(a));
}
//返回基数排序交换后的索引
public void swapNums(int [] a,int left,int right){
if (right<left) return;
int randomIndex=new Random().nextInt(right-left+1)+left;
swap(a,left,randomIndex); //交换基准元素
int temp=a[left];
int lt=left; // <基准的序列的末尾元素，初始化left
int gt=right+1; //>基准的序列的开头元素，初始为right+1
int i = left + 1;
while(i<gt)
{
if (a[i]<temp){
swap(a,i,lt+1);
lt++; //<基准的索引++
i++; //此时是置换了一个==基准的到前面，所以不需要继续验证，直接++
}else if (a[i]>temp){
swap(a,i,gt-1);
gt--; //此时是从将大于基准的数置换到后边gt-1的位置，置换到i的数字仍然需要验证，所以i不动
}else{
i++;
}
}
swap(a,left,lt);
swapNums(a,left,lt-1);
swapNums(a,gt,right);
}
public void swap(int a[],int p,int q){
int temp=a[q];
a[q]=a[p];
a[p]=temp;
}
}