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.Scanner;

public class Main {

	public static void main(String[] args) {
		try (Scanner sc = new Scanner(System.in)) {
			int n = sc.nextInt();
			int k = sc.nextInt();
			long[] x = new long[n];
			int plus = 0;
			boolean plusFlg = false;
			for (int i = 0; i < n; i++) {
				x[i] = sc.nextLong();
				if (!plusFlg && 0 <= x[i]) {
					plusFlg = true;
					plus = i;
				}
			}
			long[] arrPlus;
			long[] arrMinus;
			if (plusFlg) {
				arrPlus = new long[n - plus];
				arrMinus = new long[plus];
				for (int i = 0; i < n - plus; i++) {
					if (i < arrPlus.length) {
						arrPlus[i] = x[plus + i];
					}
					if (i < arrMinus.length) {
						arrMinus[i] = -x[plus - 1 - i];
					}
				}
			} else {
				arrPlus = new long[0];
				arrMinus = new long[n];
				for (int i = 0; i < n; i++) {
					arrMinus[i] = -x[n - 1 - i];
				}
			}

			long min = Long.MAX_VALUE;
			if (arrPlus.length == 0) {
				min = arrMinus[k - 1];
			} else if(arrMinus.length == 0) {
				min = arrPlus[k - 1];
			} else {
				for (int i = 0; i <= k; i++) {
					if (i == 0 && k <= arrMinus.length) {
						if (arrMinus[k - 1] < min) {
							min = arrMinus[k - 1];
						}
					} else if (i == k && k <= arrPlus.length) {
						if (arrPlus[k - 1] < min) {
							min = arrPlus[k - 1];
						}
					} if (i < arrPlus.length && k - i < arrMinus.length) {
						long tmp = 0;
						if (arrPlus[i - 1] < arrMinus[k - i - 1]) {
							tmp = arrPlus[i - 1] * 2 + arrMinus[k - i - 1];
						} else {
							tmp = arrPlus[i - 1] + arrMinus[k - i - 1] * 2;
						}
						if (tmp < min) {
							min = tmp;
						}
					}
				}
			}
			System.out.println(min);
		}
	}
}