java - 如何创建一个java循环来创建一个带有平方数的三角形？

Question

我已经广泛搜索了有关此主题的信息，但没有结果。我真的很挣扎于 Java 循环。

我了解了 For/While 循环的总体思路，但是当真正开始编程时，我遇到了一个又一个错误......

我尝试编写我的程序并理解它的逻辑，但我似乎无法让程序执行我想要它执行的操作。

手头的任务:

Write a program using a Scanner that asks the user for a number n between 1 and 9 (inclusive). The program prints a triangle with n rows. The first row contains only the square of 1, and it is right-justified. The second row contains the square of 2 followed by the square of 1, and is right justified. Subsequent rows include the squares of 3, 2, and 1, and then 4, 3, 2 and 1, and so forth until n rows are printed.

Assuming the user enters 4, the program prints the following triangle to the console

          1
       4  1
    9  4  1
16  9  4  1

For full credit, each column should be 3 characters wide and the values should be right justified.

到目前为止，我已经很接近了(暂时不包括用户输入，只是试图至少掌握循环方面，然后我将继续努力):

public class MyClass { 
    public static void main(String args[]) {
        int rows = 4; // this is the value that the user will enter for # of rows
        for (int i = 1; i <= rows; i++) {
            for (int j = i; j >= 1; j--) {
                System.out.print((j*j)+" ");
            }
            System.out.println();
        }
    }
}

打印:

 1
 4 1
 9 4 1
 16 9 4 1 

Answer 1

你有两个问题。

首先，您需要在左侧填充数字，以在 3 个字符的空间中生成数字。看System.out.printf("%3d", ...)

其次，您需要打印出额外的空白列。第一行有 3 个空白列，第二行有 2 个空白列，第三行有 1 个空白列，最后一行有 0 个空白列。听起来像是另一个内部循环。