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.*;

public class Main {
	//constant
	public static final String YES = "YES";
	public static final String NO = "NO";
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		//int age = sc.nextInt(); //整数の入力
		int n = sc.nextInt();
		int k = sc.nextInt();
		int count = 0;
		
		for (int a = 1; a <= n; a++) {
			for (int b = 1; b <= n; b++) {
				for (int c = 1; c <= n; c++) {
					if (((a + b) % k == 0) && ((b + c) % k == 0) && ((c + a) % k == 0)) {
						count++;
					}
				}
			}
		}
		System.out.println(count);
	}
}