Problem:
Score : 300 points

Problem Statement

You are given integers N and K. Find the number of triples (a,b,c) of positive integers not greater than N such that a+b,b+c and c+a are all multiples of K.
The order of a,b,c does matter, and some of them can be the same.

Constraints

1 \leq N,K \leq 2\times 10^5

N and K are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of triples (a,b,c) of positive integers not greater than N such that a+b,b+c and c+a are all multiples of K.

Sample Input 1

3 2

Sample Output 1

9

(1,1,1),(1,1,3),(1,3,1),(1,3,3),(2,2,2),(3,1,1),(3,1,3),(3,3,1) and (3,3,3) satisfy the condition.

Sample Input 2

5 3

Sample Output 2

1

Sample Input 3

31415 9265

Sample Output 3

27

Sample Input 4

35897 932

Sample Output 4

114191

Solution in Scala (2.11.7) (judge verdict: Wrong Answer)

object Main {
  import java.util.Scanner

  implicit class RichScanner(sc: Scanner) {
    def readStrings(n: Int): Array[String] = Array.fill(n) { sc.next() }
    def readInts(n: Int): Array[Int] = Array.fill(n) { sc.nextInt() }
    def readLongs(n: Int): Array[Long] = Array.fill(n) { sc.nextLong() }
    def readLineStrings: Array[String] = sc.nextLine().split(' ')
    def readLineInts: Array[Int] = readLineStrings.map(_.toInt)
    def readLineLongs: Array[Long] = readLineStrings.map(_.toLong)
  }

  def main(args: Array[String]): Unit = solve(new Scanner(System.in))

  def solve(sc: Scanner): Unit = {
    val Array(n, k) = sc.readInts(2)
    val possibleMods = Seq(0) ++ { if (k % 2 == 0) Seq(k / 2) else Nil }
    val answer = possibleMods.map(m => {
      val numbers = (1 to n).count(_ % k == m)
      scala.math.pow(numbers, 3).toInt
    })
    println(answer.sum)
  }
}