Printing array of multi-digit elements in reverse order in ruby

Question

How to print an array of elements in reverse order not just single digit number but also multi-digit numbers.

[2, 5, 6 7]

It should print the array elements in reverse order as 7 6 5 2 by following a space for each number.

I already wrote the code for this.

   puts "Enter the array elements"
    arr = gets.strip
    arr = arr.split(' ').map(&:to_i)
    x = arr.reverse_each {|f| }
    z = x.join(" ")
    print z.reverse

That is cool with single digit numbers, how can I reverse the multi-digit numbers in an array of inputs given by the user input like:

[45, 76, 87 ] # this should reverse the array as `87 76 45`


[556, 674, 878 ] # this should reverse the array as `878 674 556`
[8797, 7347, 9374 ] # this should reverse the array as `9374 7374 8797`

n is just used to know many elements does the array contain. However, I didn't use n in the above code. Maybe I should remove that code.! — Prabhakar--PK
– Prabhakar--PK, Commented Mar 9, 2016 at 6:13
I don't have time to post an answer, but here's a hint: two Ruby core classes have a reverse method, Array and String. You are using the latter one. — Stefan
– Stefan, Commented Mar 9, 2016 at 6:16
Thanks for the hit. Am getting the same output [34, 54,76] => [67, 45, 43]' with both reverse` methods reverse_each and reverse which is not I want. — Prabhakar--PK
– Prabhakar--PK, Commented Mar 9, 2016 at 6:20

Shannon Scott Schupbach · Accepted Answer · 2016-03-09 06:22:31Z

5

If you like one-liners:

gets.strip.split(' ').reverse.join(' ')

This will take the input 1 2 3 45 678 9 and convert it to "9 678 45 3 2 1"

answered Mar 9, 2016 at 6:22

Shannon Scott Schupbach

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3 Comments

Prabhakar--PK Over a year ago

#Optmized code. This worked like a charm!. Thank you.

Prabhakar--PK Over a year ago

shouldn't it be 9 876 54 3 2 1 ? instead of your posted output 9 678 45 3 2 1

Shannon Scott Schupbach Over a year ago

No. It would be 9 876 54 3 2 1 if you reversed the string. In my solution, reverse is being called on the output of split which is an array. This reverses the order of the elements in the array, but not the content of the elements themselves.

Uri Agassi · Accepted Answer · 2016-03-09 07:10:03Z

4

Input: [8797, 7347, 9374 ]

Output: "9374 7374 8797"

arr = gets.chomp
arr = arr.split(' ').map(&:to_i)
x = arr.reverse.join(' ')
print x

Use reverse and join chained and it should return a String type that joined your reversed array.

edited Mar 9, 2016 at 7:10

Uri Agassi

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answered Mar 9, 2016 at 6:20

philip yoo

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4 Comments

Aleksei Matiushkin Over a year ago

Please next time use “edit” to modify/update/correct the already posted answer, not just delete the old one and post the new version as a separate answer. Plus, the reference to Array#reverse was helpful.

philip yoo Over a year ago

@mudasobwa Sorry about that, will definitely do that next time

Prabhakar--PK Over a year ago

@philip yoo, Perfect solution. Thank you.

philip yoo Over a year ago

@Packer hey check out Scott's solution as well. I realized you don't need to change them to Integer type, but rather just split, reverse, then join again. :)

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