java快速排序

Posted 2020-10-16

import java.util.Arrays;

public class QuickSort {
	public static void main(String[] args) {
		int[] a = { 34, 1, 99, 44, 89, 42, 31, 6, 3 };
		System.out.println(Arrays.toString(a));
		quickSort(a, 0, a.length - 1);
		System.out.println(Arrays.toString(a));
	}

	public static void quickSort(int[] arr, int left, int right) {
		if (left >= right) {
			return;
		}
		int i = left;
		int j = right;
		int key = arr[left];
		while (i < j) {
			while (i < j && arr[j] > key) {// 这两个while不能交换
				j--;
			}
			arr[i] = arr[j];
			while (i < j && arr[i] < key) {
				i++;
			}
			arr[j] = arr[i];
		}
		arr[i] = key;
		quickSort(arr, i + 1, right);
		quickSort(arr, left, i - 1);

	}
}