快速排序-Java版本

具体讲解：快速排序

import java.util.Arrays;

/**
 * @Author: wangshiyu javapub rodert
 * @Date: 2021/3/28 15:04
 */
public class MyQuickSort {

    public static void main(String[] agrs) {
        MyQuickSort myQuickSort = new MyQuickSort();
        int[] arr = {3, 1, 5, 2, 4};
        myQuickSort.quickSort(arr, 0, arr.length - 1);
        for (int i : arr
        ) {
            System.out.println(i);
        }
    }

    public int[] quickSort(int[] arr, int left, int right) {
        System.out.println(Arrays.toString(arr));
        if (left < right) {
            int partitionIndex = partition(arr, left, right);
            quickSort(arr, left, partitionIndex - 1);
            quickSort(arr, partitionIndex + 1, right);
        }
        return arr;
    }

    public int partition(int[] arr, int left, int right) {
        // 设定基准值（pivot）
        int pivot = left;
        int index = pivot + 1;
        for (int i = index; i <= right; i++) {
            if (arr[i] < arr[pivot]) {
                swap(arr, i, index);
                index++;
            }
        }
        swap(arr, pivot, index - 1);
        return index - 1;
    }

    public void swap(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }


}