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: Runtime Error)

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.Scanner;

public class Main {
	public static void main(String[]args) {
		try(Scanner scan = new Scanner(System.in)){
			
			int N = scan.nextInt();
			int K = scan.nextInt();
			
			int[]x = new int[N];
			Deque<Integer>que = new ArrayDeque<Integer>();
			
			
			
			ArrayList<Integer>pra = new ArrayList<Integer>();//+
			ArrayList<Integer>mai = new ArrayList<Integer>();//-
			
			for(int i = 0;i<N;i++) {
				x[i] = scan.nextInt();
				if(x[i]>=0)pra.add(x[i]);
				else mai.add(x[i]);
			}
			
			Collections.sort(mai, Collections.reverseOrder());
			
			if(pra.size()==0) {
				System.out.println(Math.abs(mai.get(K-1)));
				return;
			}else if(mai.size()==0) {
				System.out.println(pra.get(K-1));
				return;
			}
			
			
			int p = 0;
			int m = 0;
			
			while(true) {
				
				int M = Math.abs(mai.get(m));
				
				if(pra.get(p)<=M) {
					p++;
				}else {
					m++;
				}
				
				if(p+m+2==K)break;
			}
			
			
			
			System.out.println(2*Math.abs(mai.get(m))+pra.get(p));
			
			
			
			
		}
		
		
	}
		

}