1461번: 도서관 (탐욕)

www.acmicpc.net/problem/1461

1461번: 도서관

# 도서관
# https://www.acmicpc.net/problem/1461 (탐욕)


def run(M, books):
    books.sort()  # ((먼 책 순서로 선택해서)) 걸음수를 계산한다
    books_right = [x for x in books if x > 0]
    books_left = [x for x in books if x < 0]
    max_walk = max(min(books) * (-1), max(books))

    walk = 0
    while books_right:
        walk += books_right.pop() * (2)
        for _ in range(M - 1):
            if books_right:
                books_right.pop()

    while books_left:
        walk += books_left.pop(0) * (-2)
        for _ in range(M - 1):
            if books_left:
                books_left.pop(0)

    return walk - max_walk


N, M = map(int, input().split())
books = list(map(int, input().split()))

print(run(M, books))