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  1. Prepare
  2. Algorithms
  3. Implementation
  4. Beautiful Triplets

Beautiful Triplets

Given a sequence of integers , a triplet is beautiful if:

Given an increasing sequenc of integers and the value of , count the number of beautiful triplets in the sequence.

Example

There are three beautiful triplets, by index: . To test the first triplet, and .

Function Description

Complete the beautifulTriplets function in the editor below.

beautifulTriplets has the following parameters:

  • int d: the value to match
  • int arr[n]: the sequence, sorted ascending

Returns

  • int: the number of beautiful triplets

Input Format

The first line contains space-separated integers, and , the length of the sequence and the beautiful difference.
The second line contains space-separated integers .

Constraints

Sample Input

STDIN           Function
-----           --------
7 3             arr[] size n = 7, d = 3
1 2 4 5 7 8 10  arr = [1, 2, 4, 5, 7, 8, 10]

Sample Output

3

Explanation

There are many possible triplets , but our only beautiful triplets are , and by value, not index. Please see the equations below:



Recall that a beautiful triplet satisfies the following equivalence relation: where .