怎么把所有素数的总和放在前面，然后是这些素数本身。

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英文:

How do i put the total sum of prime numbers first, then the prime numbers below it

问题

我目前正在使用这段代码，我试图首先输出质数的总和，然后是质数列表。

以下是我的代码：

  1. import java.util.*;
  3. public class PrimeTime {
  5.     public static void main(String[] args) {
  6.         
  7.         Scanner sc = new Scanner(System.in);
  8.         
  9.         int r, s = 0;
  10.         
  11.         System.out.print("输入数字：");
  12.         r = sc.nextInt();
  13.         
  14.         System.out.println();
  15.         
  16.         for (int i = 2; i < r; i++) {
  17.             
  18.             int f = 0;
  19.             
  20.             for (int j = 2; j < i; j++) {
  21.                 
  22.                 if (i%j == 0)
  23.                     f = 1;
  24.             }
  25.             
  26.             if (f == 0) {
  27.                 
  28.                 System.out.print(i + " ");
  29.                 s = s + 1;
  30.             }
  31.             
  32.         }
  33.         System.out.println("N =" + s);
  34.     }
  35.     
  36. }

这是我得到的结果：

  1. 输入数字：10
  3. 2 3 5 7 N = 4

但是我所期望的结果是：

  1. 输入数字：10
  3. N = 4
  4. 2 3 5 7

我不知道如何实现，我尝试了将S.O.P放在不同的位置，但是我无法弄清楚如何实现。

英文:

I'm currently using this code, and I'm trying to output the total sum of how many prime numbers first and then the prime numbers list

Here is my code:

  1. import java.util.*;
  3. public class PrimeTime {
  5.     public static void main(String[] args) {
  6.         
  7.         Scanner sc = new Scanner(System.in);
  8.         
  9.         int r, s = 0;
  10.         
  11.         System.out.print(&quot;Input number: &quot;);
  12.         r = sc.nextInt();
  13.         
  14.         System.out.println();
  15.         
  16.         for (int i = 2; i &lt; r; i++) {
  17.             
  18.             int f = 0;
  19.             
  20.             for (int j = 2; j &lt; i; j++) {
  21.                 
  22.                 if (i%j == 0)
  23.                     f = 1;
  24.             }
  25.             
  26.             if (f == 0) {
  27.                 
  28.                 System.out.print(i+ &quot; &quot;);
  29.                 s = s +1;
  30.             }
  31.             
  32.         }
  33.         System.out.println(&quot;N =&quot; +s);
  34.     }
  35.     
  36. }

This is the result I get:

  1. Input number: 10
  3. 2 3 5 7 N = 4

But what I'm looking for is this result:

  1. Input number: 10
  3. N = 4
  4. 2 3 5 7

I don't know how, I tried putting the S.O.P in different places and I can't figure out how.

答案1

得分: 0

如果你想在显示 N = 4 之前显示 2 3 5 7，你可以将这些数字（即 2 3 5 7）附加到一个 StringBuilder，然后在打印 N = 4 之后打印相同的内容，例如：

  1. import java.util.Scanner;
  3. public class Main {
  4.     public static void main(String[] args) {
  5.         Scanner sc = new Scanner(System.in);
  6.         int r, s = 0;
  7.         StringBuilder numbers = new StringBuilder();
  9.         System.out.print("Input number: ");
  10.         r = sc.nextInt();
  12.         System.out.println();
  14.         for (int i = 2; i < r; i++) {
  15.             int f = 0;
  17.             for (int j = 2; j <= Math.sqrt(i); j++) {
  19.                 if (i % j == 0)
  20.                     f = 1;
  21.             }
  23.             if (f == 0) {
  24.                 numbers.append(i).append(' ');// Append to StringBuilder instead of printing
  25.                 s = s + 1;
  26.             }
  27.         }
  28.         System.out.println("N =" + s);
  29.         System.out.println(numbers);
  30.     }
  31. }

一个示例运行：

  1. Input number: 10
  3. N = 4
  4. 2 3 5 7

注意： 检查素数性质，检查到 Math.sqrt(i) 就足够了，也就是说，你应该将 j < i 替换为 j <= Math.sqrt(i)。

英文:

If you want to display N = 4 before 2 3 5 7, you can append the numbers (i.e. 2 3 5 7) to a StringBuilder and print the same after printing N = 4 e.g.

  1. import java.util.Scanner;
  3. public class Main {
  4. 	public static void main(String[] args) {
  5. 		Scanner sc = new Scanner(System.in);
  6. 		int r, s = 0;
  7. 		StringBuilder numbers = new StringBuilder();
  9. 		System.out.print(&quot;Input number: &quot;);
  10. 		r = sc.nextInt();
  12. 		System.out.println();
  14. 		for (int i = 2; i &lt; r; i++) {
  15. 			int f = 0;
  17. 			for (int j = 2; j &lt;= Math.sqrt(i); j++) {
  19. 				if (i % j == 0)
  20. 					f = 1;
  21. 			}
  23. 			if (f == 0) {
  24. 				numbers.append(i).append(&#39; &#39;);// Append to StringBuilder instead of printing
  25. 				s = s + 1;
  26. 			}
  27. 		}
  28. 		System.out.println(&quot;N =&quot; + s);
  29. 		System.out.println(numbers);
  30. 	}
  31. }

A sample run:

  1. Input number: 10
  3. N =4
  4. 2 3 5 7

Note: for checking the primality, checking up to Math.sqrt(i) is sufficient i.e. you should replace j &lt; i with j &lt;= Math.sqrt(i).

答案2

得分: 0

你可以将数字存储在一个列表中，然后在循环结束后打印它们。

不用担心如果你还没有学习过列表，因为不久之后你会需要用到它们。

以下是代码部分：

  1. public static void main(String[] args) {
  3.     Scanner sc = new Scanner(System.in);
  5.     int r, s = 0;
  6.     LinkedList<Integer> list = new LinkedList<>();
  8.     System.out.print("输入数字：");
  9.     r = sc.nextInt();
  11.     System.out.println();
  13.     for (int i = 2; i < r; i++) {
  15.         int f = 0;
  17.         for (int j = 2; j < i; j++) {
  19.             if (i % j == 0)
  20.                 f = 1;
  21.         }
  23.         if (f == 0) {
  24.             list.add(i);
  25.             s = s + 1;
  26.         }
  27.     }
  28.     System.out.println("N = " + s);
  30.     for (int i = 0; i < list.size(); i++) {
  31.         System.out.print(list.get(i) + " ");
  32.     }
  33. }
英文:

You can store the numbers in a list and then print them after the loop is over <br>
Don't worry if you have not studied lists yet cause you will have to soon anyways.

here's the code:

  1.  public static void main(String[] args) {
  3.     Scanner sc = new Scanner(System.in);
  5.     int r, s = 0;
  6.     LinkedList&lt;Integer&gt; list = new LinkedList&lt;&gt;();
  8.     System.out.print(&quot;Input number: &quot;);
  9.     r = sc.nextInt();
  11.     System.out.println();
  13.     for (int i = 2; i &lt; r; i++) {
  15.         int f = 0;
  17.         for (int j = 2; j &lt; i; j++) {
  19.             if (i%j == 0)
  20.                 f = 1;
  21.         }
  23.         if (f == 0) {
  25.             //System.out.print(i+ &quot; &quot;);
  26.             list.add(i);
  27.             s = s +1;
  28.         }
  30.     }
  31.     System.out.println(&quot;N = &quot; +s);
  33.     for(int i = 0; i&lt;list.size(); i++ ) {
  34.         System.out.print(list.get(i) + &quot; &quot;);
  35.     }
  36. }

huangapple
  • 本文由 发表于 2020年10月28日 02:44:33
  • 转载请务必保留本文链接：https://go.coder-hub.com/64561012.html
  • java
  • loops
  • numbers
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