快速排序

Posted 2021-02-12 shineyoung

快速排序原理还是简单的，先确定一个基准数，最左或最右边的数，左边都比基准数小，右边大，然后交换基准数和移动后的左标（右标位置）继续直到不能进行下去

import java.awt.List;

class Sort{
    public void run(int[] list) {
        qsort(list, 0, list.length-1);
        for (int i = 0; i < list.length; i++) {
            System.out.println(list[i]);
        }
    }
    
    public int getMiddle(int[] list, int low, int high) {
        int base = list[low];
        int left = low;//上一次左标
        
        while (low < high) {
            while(low < high && list[high] >= base) {
                high--;
            }
            while(low < high && list[low] <= base) {
                low++;
            }
            int temp = list[low];
            list[low] = list[high];
            list[high] = temp;
        }
        list[left] = list[low];
        list[low] = base;
        
        return low;
    }
    
    public void qsort(int[] list, int low, int high) {
        
        if(low < high) {
            int middle = getMiddle(list, low, high);
            qsort(list, low, middle - 1);
            qsort(list, middle + 1, high);
        }
         
        
    }
    
}








public class QuickSort {
    public static void main(String[] args) {
        int []num = {3,56,45,98,23,5,81,56,90,90};
        Sort sort = new Sort();
        sort.run(num);
    }
}

有一点注意！如果基准数取最左边，一定要先移动右标（high）再左标（low）

反之相反。