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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);

		// N
		int n = scn.nextInt();
		// K
		int k = scn.nextInt();
		// outputInt
		int result = 0;

		// aループ
		for (int a = 1; a <= n; a++) {
			// bループ
			for (int b = 1; b <= n; b++) {
				// a+bの判定
				if ((a + b) % k != 0) {
					// a+bがkの倍数でない場合cを判定せず次のbを判定する
					continue;
				}
				// cループ
				for (int c = 1; c <= n; c++) {
					// a+cとb+cの判定
					if ((a + c) % k != 0 || (b + c) % k != 0) {
						// kの倍数ではないばあい次のcを判定する
						continue;
					} else {
						// a+c、b+cがkの倍数の場合結果に加算
						result++;
					}
				}
			}
		}
		
		// 出力
		System.out.println(result);
		scn.close();
	}

}