快排算法-java

public class QuickSort {
    
    public static void qkSort2(int[] nums, int left, int right) {
        if (left >= right) {
            return;
        }
        //选取
        int base = nums[left];
        int i = left, j = right;
        while (i < j) {
            //找到小于 base 的数
            while (nums[j] >= base && i < j) {
                j--;
            }

            //找到大于 base 的数
            while (nums[i] <= base && i < j) {
                i++;
            }
            //交换
            swap(nums, i, j);
        }

        //交换基数和最终 i
        swap(nums,i, left);

        qkSort2(nums, left, i - 1);
        qkSort2(nums, i + 1, right);
    }

    public static void qkSort(int[] nums, int left, int right) {
        if (left >= right) {
            return;
        }
        //选取
        int base = nums[left];
        int i = left, j = right;
        while (i < j) {
            //找到小于 base 的数
            while (nums[j] >= base && i < j) {
                j--;
            }
            //填坑
            if (i<j){
                nums[i++] = nums[j];
            }

            //找到大于 base 的数
            while (nums[i] <= base && i < j) {
                i++;
            }
            //填坑
            if (i<j){
                nums[j--]=nums[i];
            }
        }
        //用基数填到最终的i的位置
        nums[i] = base;
        qkSort(nums, left, i - 1);
        qkSort(nums, i + 1, right);
    }

    private static void swap(int[] nums, int i, int j) {
        int tmp = nums[i];
        nums[i] = nums[j];
        nums[j] = tmp;
    }


    public static void main(String[] args) {
        int[] num = {72,6,57,88,60,42,83,73,48};
        qkSort(num, 0, num.length-1);
        System.out.println(Arrays.toString(num));
        int[] num2 = {72,6,57,88,60,42,83,73,48};
        qkSort2(num2, 0, num.length-1);
        System.out.println(Arrays.toString(num2));
    }
}

运行结果:

[6, 42, 48, 57, 60, 72, 73, 83, 88]
[6, 42, 48, 57, 60, 72, 73, 83, 88]

Process finished with exit code 0