Hacker Rank Challenge - Pairs - https://www.hackerrank.com/challenges/pairs

pairs.cs

/*

https://www.hackerrank.com/challenges/pairs

Given N integers, count the number of pairs of integers whose difference is K.

Input Format

The first line contains N and K. 
The second line contains N numbers of the set. All the N numbers are unique.

Constraints

2 <= N <= 10^5
0 < K < 10^9

Each integer will be greater than 0 and at least K smaller than 2^31 - 1.
Output Format

An integer that tells the number of pairs of integers whose difference is K.

Sample Input

5 2  
1 5 3 4 2  

Sample Output

3

Explanation

There are 3 pairs of integers in the set with a difference of 2.

*/

  static int pairs(int[] a, int k)
	{
		var target = k;
		var count = 0;
		var diff = 0;
		var i = 0;
		var j = 0;
		System.Array.Sort(a);

		for (i = 0; i < a.Length - 1; i++)
		{
			for (j = i + 1; j < a.Length; j++)
			{
				diff = a[j] - a[i];

				if (diff == target)
				{
					count++;
				}
				else if (diff > target)
				{
					break;
				}
			}
		}

		return count;
	}