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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. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		// your code goes here
  13. 		Scanner sc=new Scanner(System.in);
  14. 		int n=sc.nextInt();
  15. 		int a[]=new int[n+1];
  16. 		for(int i=1;i<=n;i++)
  17. 		  a[i]=sc.nextInt();
  18.  
  19. 		//  storing pairs a[i]>a[j];
  20. 		   int pref[]=new int[n+1];
  21. 		   pref[1]=0;
  22.  
  23. 		   for(int j=2;j<=n;j++)
  24. 		   {
  25. 		   	int c=0;
  26. 		   	  for(int i=1;i<j;i++)
  27. 		   	  {
  28. 		   	  	if(a[i]>a[j])
  29. 		   	  	c++;
  30. 		   	  }
  31. 		   	  pref[j]=c;
  32. 		   }
  33.  
  34.  
  35. 		   //storing pairs a[k]>a[l]
  36. 		   int suff[]=new int[n+1];
  37.  
  38. 		   suff[n]=0;
  39.  
  40. 		   for(int k=n-1;k>=1;k--)
  41. 		   {
  42. 		   	int c=0;
  43. 		   	  for(int l=k+1;l<=n;l++)
  44. 		   	  {
  45. 		   	  	if(a[k]>a[l])
  46. 		   	  	c++;
  47. 		   	  }
  48. 		   	  suff[k]=c;
  49. 		   }
  50.  
  51. 		   int ans=0;
  52. 		   for(int j=1;j<=n;j++)
  53. 		   {
  54. 		   		for(int k=j+1;k<=n;k++)
  55. 		   		{
  56. 		   			if(a[j]<a[k])
  57. 		   			ans+=pref[j]*suff[k];
  58. 		   		}
  59. 		   }
  60.  
  61. 		   System.out.println(ans);
  62. 	}
  63. }
Success #stdin #stdout 0.14s 56552KB
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https://ideone.com/4Ak6Po
language:
Java (HotSpot 12)
created:
15 hours ago
visibility:
public

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