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

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Main {
   
    public static Integer listAll(List<Integer> list, Integer[] intArr, int n, Integer minVal) {
        if (n == 0) {
            int temMinValue = Math.abs(list.get(0)-0);
            for(int i = 1; i<list.size(); i++) {
            	temMinValue += Math.abs(list.get(i)-list.get(i-1));
            }
            if(minVal == null || minVal > temMinValue) {
            	minVal = temMinValue;
            }
            return minVal;
        }
        for (Integer integer : intArr) {                    
            if (!list.contains(integer)) { 
                list.set(list.size() - n, integer);
            } else {                                
                continue;
            }
            minVal =listAll(list, intArr, n - 1, minVal);   
            list.set(list.size() - n, -99999999);        
        }
        return minVal;
    }

    public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int N = in.nextInt();
		int M = in.nextInt();
        Integer[] numbers = new Integer[N];
		for(int i = 0; i < N; i ++) {
			numbers[i] = in.nextInt();
		}

        if (M <= 0 || numbers == null) {
            return;
        }
        List<Integer> stringList = new ArrayList<>();
        for (int i = 0; i < M; i++) {
            stringList.add(-99999999);
        }
        Integer minVal = null;
        int resultValue = listAll(stringList, numbers, M, minVal);
        System.out.println(resultValue);
    }
}