使用递归在Java中以正确格式打印钻石图案

问题描述

我的程序从文件中读取值，并使用递归方法根据这些值打印星号图案。我只是有一个问题，一切正常排队。

输出应该是这样的：

  * 
 * * 
 * * * 
 * * 
 * 
  pre> 
 
 
关于输出的格式，指示是： 
 
 
 请注意，在中心线对称（垂直）对齐，图案应该在每一行（水平）对称对齐 - 提示：使用行值来帮助空间。 
 
 
 
但我的输出如下所示： 
 
 
  * 
 * * 
 * * * 
 * * 
 * 
  
 以获得此模式：  
 
 
  public static void makePattern（int thisRow，int num）{
 if （thisRow> = num）{
 for（int i = 0; i< num; i ++）{
 System.out.print（+*+）; 
} 
 System.out.println（）; 
 
 $ b $ {
（int i = 0; i< thisRow; i ++）{
 System.out.print（+* +）; 
} 
 System.out.println（）; 
 
 makePattern（thisRow + 1，num）; 
 
（int i = 0; i< thisRow; i ++）{
 System.out.print（+*+）; 
} 
 System.out.println（）; 
 
 
 
 
 
 $ b 
 我的主要方法是： 
  import java.util.Scanner; 
 import java.io. *; 
 $ b $ public class Program3 {
 public static void main（String [] args）throws Exception {
 int num = 0; 
 int thisRow = 1; 
 java.io.File file = new java.io.File（../ instr / prog3.dat）; 
扫描仪fin =新扫描仪（文件）; $（b 
 $ b while（fin.hasNext（））{
 num = fin.nextInt（）; 
 if（num> = 0& num< = 25）
 makePattern（thisRow，num）; 
 System.out.println（）; 
} 
 fin.close（）; 
 
 
 
 
 $ p 
 $ b 
有关如何编辑我的代码以使我的输出看起来像我包含的示例模式？
解决方案
 
我们首先分析输出结果!! 
 
 
 
第一步是分析输出 
 
 
  
 
结论：
 
 
 
 
 
总数每行的字符总是 n （= 3）
 
 
空格的数量有以下模式：
 
 
  3  -   1 空格
 
  3  -   2 空格
 
   3   -  3个空格
 
   / strong>  -  3个空格
 
   5   -  3个空格 
 
 
 / p> 
 
 
  if（num  numberOfSpace s = thisRow  -  num; 
} else {
 numberOfSpaces = num  -  thisRow; 
 
 $ / code $ / pre $ 
 
 
星号总是[ n  - 数字 
 
 
 $ b $ p $  int numberOfStars = num  -  numberOfSpaces; 
  
 
 
 
 
递归应该在第6行结束，即当前行号是 n * 2  
 
 
 
所以递归方法中的返回条件应该是
 
 pre >  if（thisRow == num * 2）
 return; 
  
  
  
 
 
 
 
 
 
 
 
最终代码：将peices放在一起
 
 
 
当我们把peices放在一起时，我们得到：
 
 $ p $终止条件
 if（thisRow == num * 2）
 return; 
 
 //空格的数量
 int numberOfSpaces = 0; 
 if（num  numberOfSpaces = thisRow  -  num; 
} else {
 numberOfSpaces = num  -  thisRow; 
} 
 
 //星星数
 int numberOfStars = num  -  numberOfSpaces; 
 
 //在打印字符串之前编写字符串
 StringBuffer outputBuffer = new StringBuffer（num）; 
 for（int i = 0; i< numberOfSpaces; i ++）{
 outputBuffer.append（）; 
 
 for（int i = 0; i< numberOfStars; i ++）{
 outputBuffer.append（*）; 
} 
 
 //输出字符串
 System.out.println（outputBuffer.toString（））; 
 
 //递归
 makePattern（thisRow + 1，num）; 
} 
  
 
My program reads in values from a file and uses a recursive method to print patterns of asterisks based on those values. I'm just having a problem getting everything to line up properly.
The output is supposed to look like this:
    *
  *   *
*   *   *
  *   *
    *
Regarding the format of the output, the directions are:
"Note that the pattern is aligned symmetrically (vertically) about the center line. The pattern should be aligned symmetrically on each line (horizontally) as well- hint: use the line value to help space."
But my output looks like this:
*
*  *
*  *  *
*  *
*
The code I'm using to get this pattern:
public static void makePattern(int thisRow, int num) {
    if(thisRow >= num) {
        for(int i = 0; i < num; i++) {
            System.out.print("  " + "*" + "  ");
        }
        System.out.println();

    }
    else {
        for(int i = 0; i < thisRow; i++) {
            System.out.print("  " + "*" + "  ");
        }
        System.out.println();

        makePattern(thisRow + 1, num);

        for(int i = 0; i < thisRow; i++) {
            System.out.print("  " + "*" + "  ");
        }
        System.out.println();
    }
}
Also my main method:
import java.util.Scanner;
import java.io.*;

public class Program3 {
    public static void main(String[] args) throws Exception {
        int num = 0;
        int thisRow = 1;
        java.io.File file = new java.io.File("../instr/prog3.dat");
        Scanner fin = new Scanner(file);

        while(fin.hasNext()) {
                num = fin.nextInt();
                if(num >=0 && num <= 25)
                    makePattern(thisRow, num);
                System.out.println();
        }
        fin.close();

    }
Any suggestions on how to edit my code to make my output appear like the example pattern I included?
 解决方案 
Let's analyse the output first!!
First step is to analyse the output
Conclusions:
The total number of characters on every line is always n (=3)
Number of Spaces has the following pattern:
  3 - 1 spaces
  3 - 2 spaces
  3 - 3 spaces
  4 - 3 spaces
  5 - 3 spaces  
So
if(num < thisRow) {
  numberOfSpaces = thisRow - num;
} else {
  numberOfSpaces = num - thisRow;
}
Number of  Stars is always [n - the number of spaces]
So
int numberOfStars = num - numberOfSpaces;
And the recursion should end on the 6th line, i.e. when current line number is n*2
So the return condition in your recursive method should be
if(thisRow == num * 2)
   return;


Final Code : Putting the peices together
When we put the peices together, we get:
    public static void makePattern(int thisRow, int num) {
        //the termination condition
        if(thisRow == num * 2)
           return;

        //the number of spaces
        int numberOfSpaces = 0;
        if(num < thisRow) {
          numberOfSpaces = thisRow - num;
        } else {
          numberOfSpaces = num - thisRow;
        }

        //the number of stars
        int numberOfStars = num - numberOfSpaces;

        //compose the string before printing it
        StringBuffer outputBuffer = new StringBuffer(num);
        for (int i = 0; i < numberOfSpaces; i++){
            outputBuffer.append(" ");
        }
        for (int i = 0; i < numberOfStars; i++){
            outputBuffer.append("* ");
        }

        //print the string
        System.out.println(outputBuffer.toString());

        //recursion
        makePattern(thisRow + 1, num);
   }
                        
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