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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  
  11. 	static boolean isprime(int n)
  12. 	{
  13. 		if(n==2)
  14. 		return true;
  15. 		else if(n%2==0)
  16. 		return false;
  17. 		for(int i=3;i<=Math.sqrt(n);i+=2)
  18. 		{
  19. 			if(n%i==0)
  20. 			return false;
  21. 		}
  22. 		return true;
  23. 	}
  24. 	public static void main (String[] args) throws java.lang.Exception
  25. 	{
  26. 		// your code goes here
  27. 		Scanner sc=new Scanner(System.in);
  28. 		int t=sc.nextInt();
  29. 		while(t-->0)
  30. 		{
  31. 			int n=sc.nextInt();
  32.  
  33. 			// 2 is the only even prime no.
  34. 			if(n==2)
  35. 			System.out.println("1");
  36.  
  37. 			/* Goldbach theo
  38. 			-> any even no. can be represented as sum of 2 primes
  39. 			*/
  40. 			else if(n%2==0)
  41. 			System.out.println("2");
  42.  
  43. 			// if num is odd
  44. 			else
  45. 			{
  46. 				// if num is odd and prime , then as we know ans for prime =1
  47. 				if(isprime(n))
  48. 				System.out.println("1");
  49.  
  50. 				/* if the num is odd it can be represented as 
  51. 				odd = eve+odd (here eve , odd both shls be prime)
  52.  
  53. 				the only even prime is 2 so we need to check if n-2 is prime 
  54. 				if its prime then ans=2
  55. 				*/
  56. 				else if(isprime(n-2))
  57. 				System.out.println("2");
  58. 				/* goldbach told any odd num can be represented as sum of 1, 2 or 3 prime numbers , we 
  59. 				already tries cases for 1, 2 
  60. 				so the remaining answer is 3
  61. 				*/
  62. 				else
  63. 				System.out.println("3");
  64. 			}
  65. 		}
  66. 	}
  67. }
Success #stdin #stdout 0.15s 54532KB
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https://ideone.com/0PDo6S
language:
Java (HotSpot 12)
created:
4 days ago
visibility:
public

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