HackerRank Ruby Array – Index, Part 2 problem solution

In this HackerRank Ruby Array – Index, Part 2 problem solution Here are some other ways to access array objects in Ruby. To access the elements from the end of the list, we can use negative indices. For the array,

arr = [9, 5, 1, 2, 3, 4, 0, -1]

 > arr[-1]

 => -1

The first element of the array can be accessed using

 > arr.first

 => 9

The last element of the array can be accessed using

 > arr.last

 => -1

The first n elements of the array can be accessed using

 arr.take(3)

 => [9, 5, 1]

Everything but the first n elements of the array can be accessed using

 arr.drop(3)

 => [2, 3, 4, 0, -1]

Problem solution.

def neg_pos(arr, index)
    # return the element of the array at the position `index` from the end of the list
    # Clue : arr[-index]
    arr[-index]
end

def first_element(arr)
    # return the first element of the array
    # arr.first
    arr.first
end

def last_element(arr)
    # return the last element of the array
    # arr.last
    arr.last
end

def first_n(arr, n)
    # return the first n elements of the array
    arr.take(n)
end

def drop_n(arr, n)
    # drop the first n elements of the array and return the rest
    arr.drop(n)
end