Problem:
Score : 300 points

Problem Statement

There are N candles placed on a number line.
The i-th candle from the left is placed on coordinate x_i.
Here, x_1 < x_2 < ... < x_N holds.

Initially, no candles are burning.
Snuke decides to light K of the N candles.

Now, he is at coordinate 0.
He can move left and right along the line with speed 1.
He can also light a candle when he is at the same position as the candle, in negligible time.

Find the minimum time required to light K candles.

Constraints

1 \leq N \leq 10^5

1 \leq K \leq N

x_i is an integer.

|x_i| \leq 10^8

x_1 < x_2 < ... < x_N

Input

Input is given from Standard Input in the following format:

N K
x_1 x_2 ... x_N

Output

Print the minimum time required to light K candles.

Sample Input 1

5 3
-30 -10 10 20 50

Sample Output 1

40

He should move and light candles as follows:

Move from coordinate 0 to -10.

Light the second candle from the left.

Move from coordinate -10 to 10.

Light the third candle from the left.

Move from coordinate 10 to 20.

Light the fourth candle from the left.

Sample Input 2

3 2
10 20 30

Sample Output 2

20

Sample Input 3

1 1
0

Sample Output 3

0

There may be a candle placed at coordinate 0.

Sample Input 4

8 5
-9 -7 -4 -3 1 2 3 4

Sample Output 4

10

Solution in Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class Main{

	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);

		String[] tmp = scanner.nextLine().split(" ");
		int n  = Integer.parseInt(tmp[0]);
		int k  = Integer.parseInt(tmp[1]);
		Long a = Long.MAX_VALUE;
		int[] lst = new int[n];
		String[] tmp2 = scanner.nextLine().split(" ");

		for(int i = 0; i < n; i++) {

			lst[i] = Integer.parseInt(tmp2[i]);
		}

		for(int i = 0; i < (n - k + 1); i++) {

			int r = i + k - 1;

			if(lst[i] <= 0 && lst[r] <= 0) {

				a = Math.min(Math.abs(lst[i]), a);
			}else if(lst[i] <= 0 && lst[r] >= 0) {

				a = Math.min(Math.abs(lst[i] + lst[i] - lst[r]), a);

			}else if(lst[i] >= 0 && lst[r] >= 0){

				a = Math.min(Math.abs(lst[r]), a);
			}

		}
		System.out.println(a);
	}
}