冒泡排序O(n^2)

public class Main {
    public static void main(String[] args) {
        Random random = new Random();
        int[] nums = new int[]{random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100)};
        for (int i = nums.length - 1; i >= 0; i--) {
            for (int j = 0; j < i; j++) {
                if (nums[j] > nums[j + 1]) {
                    int temp = nums[j];
                    nums[j] = nums[j + 1];
                    nums[j + 1] = temp;
                }
            }
        }
        for (int num : nums) {
            System.out.print(num + " ");
        }
    }
}

选择排序O(n^2),

public class Main {
    public static void main(String[] args) {
        Random random = new Random();
        int[] nums = new int[]{random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100)};
        int index;
        for (int i = 0; i < nums.length; i++) {
            index = i;//每一轮记录最小值的索引
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[j] < nums[index]) {
                    index = j;
                }
            }
            if (index != i) {
                int temp = nums[i];
                nums[i] = nums[index];
                nums[index] = temp;
            }
        }
        for (int num : nums) {
            System.out.print(num + " ");
        }
    }
}

插入排序O(n^2)

public class Main {
    public static void main(String[] args) {
        Random random = new Random();
        int[] nums = new int[]{random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100), random.nextInt(100)};
        int index;
        for (int i = 1; i < nums.length; i++) {
            int rec = nums[i];
            index = i;
            for (int j = i - 1; j >= 0; j--) {
                if (nums[j] > rec) {
                    nums[index] = nums[j];
                    index = j;
                } else {
                    break;
                }
            }
            nums[index] = rec;
        }
        for (int num : nums) {
            System.out.print(num + " ");
        }
    }
}