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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. 		Integer[] arr = {1, 4, 3, 2, 5};
  13. 		System.out.println(pairsCount(arr));
  14. 	}
  15.  
  16. 	static class Node
  17. 	{
  18. 		int value;
  19. 		Node left, right;
  20. 		int rc; // right count
  21. 		int ic; // duplicate count
  22.  
  23. 		Node(int value)
  24. 		{
  25. 			this.value = value;
  26. 		}
  27. 	}
  28.  
  29. 	static int pairsCount(Integer[] arr)
  30. 	{
  31. 		int count = 0;
  32. 		Node root = new Node(arr[0]);
  33. 		for(int i=1; i<arr.length; i++)
  34. 		{
  35. 			count += insert(root, arr[i]);
  36. 		}
  37. 		return count;
  38. 	}
  39.  
  40. 	static int insert(Node n, int v)
  41. 	{
  42. 		if(v < n.value)
  43. 		{
  44. 			if(n.left == null) 
  45. 			{
  46. 				n.left = new Node(v);
  47. 				return 1 + n.rc + n.ic;
  48. 			}
  49. 			return 1 + n.rc + n.ic + insert(n.left, v);
  50. 		}
  51. 		else if(v > n.value)
  52. 		{
  53. 			if(n.right == null) 
  54. 			{
  55. 				n.right = new Node(v);
  56. 				n.rc = 1;
  57. 				return 0;
  58. 			}
  59. 			n.rc += 1;
  60. 			return insert(n.right, v);
  61. 		}
  62. 		else
  63. 		{
  64. 			n.ic += 1;
  65. 			return n.rc;
  66. 		}
  67. 	}
  68. }
Success #stdin #stdout 0.07s 47056KB
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https://ideone.com/FTX9uO
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
public

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