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Swap Numbers(CODEEVAL)

文中の文字列の前後を入れ替える問題。今回はつまらない。

CHALLENGE DESCRIPTION:

Write a program that, given a sentence where each word has a single digit positive integer as a prefix and suffix, swaps the numbers while retaining the word in between. Words in the sentence are delimited from each other by a space.

INPUT SAMPLE:

The first argument is a path to a file. Each line of the input file contains one test case represented by a sentence. Each word in the sentence begins and ends with a single digit positive integer i.e. 0 through 9. Assume all characters are ASCII.

4Always0 5look8 4on9 7the2 4bright8 9side7 3of8 5life5
5Nobody5 7expects3 5the4 6Spanish4 9inquisition0

OUTPUT SAMPLE:

0Always4 8look5 9on4 2the7 8bright4 7side9 8of3 5life5
5Nobody5 3expects7 4the5 4Spanish6 0inquisition9

CONSTRAINTS:

  1. The suffix and the prefix of each word may be equal.
  2. Sentences are form 1 to 17 words long.
  3. The number of test cases is 40.

My Code

#!/usr/bin/env ruby -w

def swap_numbers(line)
  line.split.map do |word|
    first = word[0]
    last = word[-1]
    word[0] = last
    word[-1] = first
    word
  end.join(" ")
end

ARGF.each_line do |line|
  puts swap_numbers(line.chomp)
end