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.

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

Function Description

Complete the beautifulTriplets function in the editor below. It must return an integer that represents the number of beautiful triplets in the sequence.

beautifulTriplets has the following parameters:

• d: an integer
• arr: an array of integers, sorted ascending

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

Output Format

Print a single line denoting the number of beautiful triplets in the sequence.

Sample Input

7 3
1 2 4 5 7 8 10

Sample Output

3

Explanation

The input sequence is , and our beautiful difference . 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 .

 php

<?php

// Complete the beautifulTriplets function below.

function beautifulTriplets($d, $arr) {

sort($arr);

$cnt = 0;

foreach ($arr as $v) {

$num1 = $v + $d;

$num2 = $num1 + $d;

if(in_array($num1, $arr) && in_array($num2, $arr)) {

$cnt++;

}

}

return $cnt;

}

$fptr = fopen(getenv("OUTPUT_PATH"), "w");

$stdin = fopen("php://stdin", "r");

fscanf($stdin, "%[^\n]", $nd_temp);

$nd = explode(' ', $nd_temp);

$n = intval($nd[0]);

$d = intval($nd[1]);

fscanf($stdin, "%[^\n]", $arr_temp);

$arr = array_map('intval',
preg_split('/ /', $arr_temp, -1, PREG_SPLIT_NO_EMPTY));

$result = beautifulTriplets($d, $arr);

fwrite($fptr, $result . "\n");

fclose($stdin);

fclose($fptr);