java如何确定正方形的数学三角形的角度？

Question

我需要修复底部显示的输出，我有输出正确数学值的代码 但它并没有输出我在下面提供的示例输出所期望的正确角度。（我知道这对大多数stack用户来说都很简单，但我是java初学者，这让我很困惑）。我还没有想到我能做些什么来解决这个问题，并把它放在正确的角度

说明：

-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

代码：

import java.util.Scanner;

public class Triangle {

public static void main(String[] args) {

    Scanner scan = new Scanner(System.in);
    System.out.println("Please enter a number between 1 and 9 inclusive:");
    int n = scan.nextInt();
    for (int i = 1 ; i <=n; i++) {
        for (int j = n-i; j >=1; j--) {
            System.out.print("");
        }
        for (int k = i; k <= n; k++ ) {
            System.out.print("  " + i * i);
        }
        System.out.println("  ");
    }
    scan.close();
}
}

我的输出：

Please enter a number between 1 and 9 inclusive:  4

  1  1  1  1  
  4  4  4  
  9  9  
  16  

Answer 1

TL；博士用笔和纸解决恼人的逻辑问题

解决这类问题的最简单方法是根据迭代的变量写出打印的位置。一个额外的变量col帮助我们跟踪当前列，该列与我们迭代的方向相反

我们可以注意到，如果我们从右向左数列，这个数字正好对应于列的位置，平方

我们还可以注意到，空格的数量等于n——比当前行迭代少一个（因为它从0开始）

          1 
       4  1 
    9  4  1 
16  9  4  1 

抛开这些废话不谈，我们可以使用String.format()使两位数的输出为偶数

public static void main(String[] args) {

    Scanner scan = new Scanner(System.in);
    System.out.println("Please enter a number between 1 and 9 inclusive:");
    int n = scan.nextInt();

    for (int i = n; i > 0; i ) {
        int col = 4;

        // Print spaces
        for (int j = 0; j < (i-1); j++) {
            System.out.print("   ");
            col ;
        }

        // Print numbers
        for (int j = (i-1); j < n; j++) {
            System.out.print(String.format("%2d", col*col) + " ");
            col ;
        }

        System.out.println();
    }

    scan.close();
}

Answer 2

下面是一个简短的变体

    for (int row = 1; row <= n; row ++) {
        for (int col = n; col >= 1; col ) {
            if (col <= row) {
                System.out.print(String.format("%2d ", col * col));
            } else {
                System.out.print("   ");
            }
        }
        System.out.println();
    }

以下是为输入9生成的输出：

                         1 
                      4  1 
                   9  4  1 
               16  9  4  1 
            25 16  9  4  1 
         36 25 16  9  4  1 
      49 36 25 16  9  4  1 
   64 49 36 25 16  9  4  1 
81 64 49 36 25 16  9  4  1