我的三角形打印了两次。怎么解决？

huangapple
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英文:

My triangle printed out twice. How to solve it?

问题

  1. package javaapplication4;
  3. public class NewClass6 {
  4.   public static void main(String[] args) {
  5.     for (int i = 1; i <= 9; i++) {
  6.       int sum = 1;
  7.       for (int j = 1; j <= i; j++) {
  8.         if (j % 2 != 0) {
  9.           System.out.print(j);
  10.           sum *= j;
  11.         }
  12.         if (j == i)
  13.           System.out.print("=");
  14.         else if (j % 2 != 0)
  15.           System.out.print("*");
  16.       }
  17.       System.out.println(sum);
  18.     }
  19.   }
  20. }
英文:

It printing out * and = twice

I'm making a sequence triangle (again), now with odd numbers only and multiplying.
It appear to be printing * and = twice.

The result should be like this:
1 = 1

1 * 3=3

1* 3* 5=15

etc

  1. package javaapplication4;
  3. public class NewClass6 {
  4.   public static void main(String[] args) {
  5.     for (int i = 1; i &lt;= 9; i++) {
  6.       int sum = 1;
  7.       for (int j = 1; j &lt;= i; j++) {
  8.         if (j % 2 != 0) {
  9.           System.out.print(j);
  10.           sum *= j;
  11.         }
  12.         if (j == i)
  13.           System.out.print(&quot;=&quot;);
  14.         else if (j % 2 != 0)
  15.           System.out.print(&quot;*&quot;);
  16.       }
  17.       System.out.println(sum);
  18.     }
  19.   }
  20. }

答案1

得分: 3

这是因为您在循环中将 i 从 1 ~ 9 循环，而将 j 从 1~i 循环，每次只增加1。

需要循环的是奇数，所以每次增加2。
因此代码应该是：

  1. package javaapplication4;
  3. public class NewClass6 {
  4.   public static void main(String[] args) {
  5.     for (int i = 1; i <= 9; i += 2) {
  6.       int sum = 1;
  7.       for (int j = 1; j <= i; j += 2) {
  8.         if (j % 2 != 0) {
  9.           System.out.print(j);
  10.           sum *= j;
  11.         }
  12.         if (j == i)
  13.           System.out.print("=");
  14.         else if (j % 2 != 0)
  15.           System.out.print("*");
  16.       }
  17.       System.out.println(sum);
  18.     }
  19.   }
  20. }
英文:

This happens because you have looped i from 1 ~ 9 and j from 1~i by creasing only one per step.

It is needed to loop only odd numbers so increase 2 per step.
So for (int i = 1; i &lt;= 9; i +=2) {

  1. package javaapplication4;
  3. public class NewClass6 {
  4.   public static void main(String[] args) {
  5.     for (int i = 1; i &lt;= 9; i+=2) {
  6.       int sum = 1;
  7.       for (int j = 1; j &lt;= i; j+=2) {
  8.         if (j % 2 != 0) {
  9.           System.out.print(j);
  10.           sum *= j;
  11.         }
  12.         if (j == i)
  13.           System.out.print(&quot;=&quot;);
  14.         else if (j % 2 != 0)
  15.           System.out.print(&quot;*&quot;);
  16.       }
  17.       System.out.println(sum);
  18.     }
  19.   }
  20. }

答案2

得分: 3

  1. 简洁起见！
  3.     StringBuilder buf = new StringBuilder();
  5.     for (int i = 1, mul = i; i <= 9; i += 2) {
  6.         if (buf.length() > 0)
  7.             buf.append('*');
  8.     
  9.         buf.append(i);
  10.         mul *= i;
  11.     
  12.         System.out.format("%s=%d\n", buf, mul);
  13.     }
  15. **输出：**
  17.     1=1
  18.     1*3=3
  19.     1*3*5=15
  20.     1*3*5*7=105
  21.     1*3*5*7*9=945
英文:

Be simple!

  1. StringBuilder buf = new StringBuilder();
  3. for (int i = 1, mul = i; i &lt;= 9; i += 2) {
  4.     if (buf.length() &gt; 0)
  5.         buf.append(&#39;*&#39;);
  7.     buf.append(i);
  8.     mul *= i;
  10.     System.out.format(&quot;%s=%d\n&quot;, buf, mul);
  11. }

Output:

  1. 1=1
  2. 1*3=3
  3. 1*3*5=15
  4. 1*3*5*7=105
  5. 1*3*5*7*9=945

答案3

得分: 2

以下是翻译后的代码部分：

第一段代码：

  1. for (int i = 1; i <= 9; i++) {
  2.     if (i % 2 != 0) {
  3.         int sum = 1;
  4.         for (int j = 1; j <= i ; j++) {
  5.             if(j % 2 != 0)
  6.             {
  7.                 System.out.print(j);
  8.                 sum *= j; 
  9.                 if (j == i) 
  10.                     System.out.print("=");
  11.                 else if (j % 2 != 0)
  12.                     System.out.print("*");    
  13.             }
  14.         }
  15.         System.out.println(sum);
  16.     }
  17. }

第二段代码：

  1. for (int i = 1; i <= 9; i += 2) {
  2.     int sum = 1;
  3.     for (int j = 1; j <= i ; j += 2) {
  4.         System.out.print(j);
  5.         sum *= j; 
  6.         if (j == i) 
  7.             System.out.print("=");
  8.         else if (j % 2 != 0)
  9.             System.out.print("*");    
  10.     }
  11.     System.out.println(sum);
  12. }
英文:

You're considering odd numbers in internal loop but you're not doing so in outer loop, either skip even numbers by changing i++ to i += 2 or add another if block for checking if i is not even:

  1. for (int i = 1; i &lt;= 9; i++) {
  2.     if (i % 2 != 0) { // Skipping outer loop&#39;s even numbers
  3.         int sum = 1;
  4.         for (int j = 1; j &lt;= i ; j++) {
  5.             if(j % 2 != 0)
  6.             {
  7.                 System.out.print(j);
  8.                 sum *= j; 
  9.                 if (j == i) 
  10.                     System.out.print(&quot;=&quot;);
  11.                 else if (j % 2 != 0)
  12.                     System.out.print(&quot;*&quot;);    
  13.             }
  15.         }
  17.         System.out.println(sum);
  18.     }
  19. }

Or skip even elements by += 2 rather than ++(I would suggest using this)

  1. for (int i = 1; i &lt;= 9; i += 2) {
  2.     int sum = 1;
  3.     for (int j = 1; j &lt;= i ; j += 2) {
  4.         System.out.print(j);
  5.         sum *= j; 
  6.         if (j == i) 
  7.             System.out.print(&quot;=&quot;);
  8.         else if (j % 2 != 0)
  9.             System.out.print(&quot;*&quot;);    
  10.     }
  11.     System.out.println(sum);
  12. }

huangapple
  • 本文由 发表于 2020年10月16日 23:54:08
  • 转载请务必保留本文链接：https://go.coder-hub.com/64392527.html
  • for-loop
  • java
  • loops
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