冒泡排序和打印菱形

冒泡排序
1.原理：比较两个相邻的元素，将值大的元素交换到右边
N个数字要排序完成，总共进行N-1趟排序，每i趟的排序次数为(N-i)次，所以可以用双重循环语句，外层控制循环多少趟，内层控制每一趟的循环次数

     int[] arr = {3,5,1,4,2};
        for (int i = 0; i arr[j+1]){
                    int temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                }
            }
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i]+" ");
        }

打印菱形

public static void main(String[] args) {
        System.out.println("请输入菱形行数");
        Scanner sc = new Scanner(System.in);
        System.out.print("输入行数：");
        int num = sc.nextInt();
        for (int i = 0; i  i+1; j--) {
                System.out.print(" ");
            }
            for (int k = 0; k <= 2*i-1; k++) {
                System.out.print("*");
            }
            System.out.println("*");
        }
        for (int i = 1; i < num; i++) {
            for (int j = 0; j < i; j++) {
                System.out.print(" ");
            }
            for (int k = 0; k < 2*(num-i)-1 ; k++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }