无法使用二维数组制作等边三角形

i am preparing my self for the interview. I have to make a equilateral triangle Using 7X7 2D array.

我正在为面试做准备。我必须使用7X7 2D阵列制作等边三角形。

I tried the below code but i am confused like what should i do in my code so that i can make a equilateral triangle?

我尝试了下面的代码,但我很困惑,我应该怎么做我的代码,以便我可以做一个等边三角形?

    package learn.basic.corejava;

public class ArrayExample {


    public void two_equilateral_D()
    {
        System.out.println("Demonstrating 2D 3X3 Equal trngle");
        int twoD[][]=new int[7][7];
        int i,j,k=0;

        for(i=0;i<7;i++)
        {
            for(j=0;j<7;j++)
            {       
                twoD[i][j]=k>9?0:k; 
                k++;
            }   
        }

        for(i=0;i<7;i++)
        {  
              for(j=i+3;j<7;j++) {
             System.out.print(twoD[i][j]+"   ");   
              }
            System.out.println("");
        }

    }  

    public static void main(String args[] )
    {
        ArrayExample obj=new ArrayExample();
        //System.out.println("Average value of the array="+obj.calculate_average());
        obj.two_equilateral_D();

    }
}

But this code gives me output like

但是这段代码给了我类似的输出

Demonstrating 2D 3X3 Equal trngle
3   4   5   6   
0   0   0   
0   0   
0   

Desired output like this

期望的输出像这样

3 个解决方案

#1

To approach your problem, you should start by breaking it down into two smaller sub-problems:

要解决您的问题,您应该首先将其分解为两个较小的子问题:

1. Generate the desired triangular matrix of values (it's called Pascal's triangle, among other things).

   生成所需的三角形值矩阵(其中称为Pascal的三角形)。

2. Display the values nicely.

   很好地显示值。

Each of the problems is fairly straightforward by itself. Try your hand at them and come back if you need help.

每个问题本身都相当简单。试试你的手,如果你需要帮助,请回来。

#2

I think the special condition (the hard part) shouldn't be in the loop condition, but in a new condition inside the nested loop.

我认为特殊条件(硬部分)不应该处于循环条件中,而是处于嵌套循环内的新条件中。

1. You need to iterate over the whole matrix, instead of limiting the nested loop (with variable j).

   您需要迭代整个矩阵,而不是限制嵌套循环(使用变量j)。

2. Inside the loop, add an if() statement to check whether you want to display the value or just a space. This condition is what you should work on.

   在循环内部,添加if()语句以检查是要显示值还是仅显示空格。这种情况是你应该做的。

The code should look like this:

代码应如下所示:

for (int i = 0; i < 7; i++) {
    for (int j = 0; j < 7; j++) {
        if (condition) {
            System.out.print(twoD[i][j]+"   ");   
        } else {
            System.out.print("    "); // note the extra space here to make up for a number
        }
    }
    System.out.println("");
}

---

EDIT: You radically changed your question, there is now two problems:

编辑:你从根本上改变了你的问题,现在有两个问题:

1. You have to initialize your matrix with Pascal's Triangle values.

   您必须使用Pascal的三角形值初始化矩阵。

2. The output you now posted is not a console output, you'll have to make choices as to where to put the spaces, and how to deal with 2-digit numbers. The easiest is to make every cell take 2 characters (either a space and a digit, or 2 digits).

   您现在发布的输出不是控制台输出,您必须选择放置空格的位置以及如何处理2位数字。最简单的方法是使每个单元格占用2个字符(空格和数字,或2位数字)。

#3

in the second nested loop

在第二个嵌套循环中

for(i=0;i<7;i++)
{  
      for(j=i+3;j<7;j++) {
     System.out.print(twoD[i][j]+"   ");   
      }
    System.out.println("");
}

you are removing any values beyond index 3 which is why you are only going to 4 numbers instead of 7

你正在删除索引3之外的任何值,这就是为什么你只需要4个数而不是7个

After writing to the 7x7 array use

写入7x7阵列后使用

int num=0;
for(i=1;i<7;i++)
{  
    num=0;
    for(j=7;j>7-i;j--) 
    {
        System.out.print(twoD[i][j]+"   ");  
        System.out.print(twoD[i][num]+"   ");
        num++;
    }
    System.out.println("");
}

This should give the desired output

这应该给出所需的输出