READ MORE(CodeEval)

すごい久しぶりにcodeeval。

CHALLENGE DESCRIPTION:

You are given a text. Write a program which outputs its lines according to the following rules:

1. If line length is ≤ 55 characters, print it without any changes.
2. If the line length is > 55 characters, change it as follows:
  1. Trim the line to 40 characters.
  2. If there are spaces ‘ ’ in the resulting string, trim it once again to the last space (the space should be trimmed too).
  3. Add a string ‘... <Read More>’ to the end of the resulting string and print it.

INPUT SAMPLE:

The first argument is a file. The file contains a text.

For example:

Tom exhibited.
Amy Lawrence was proud and glad, and she tried to make Tom see it in her face - but he wouldn't look.
Tom was tugging at a button-hole and looking sheepish.
Two thousand verses is a great many - very, very great many.
Tom's mouth watered for the apple, but he stuck to his work.

OUTPUT SAMPLE:

Print to stdout the text lines with their length limited according to the rules described above.

For example:

Tom exhibited.
Amy Lawrence was proud and glad, and... <Read More>
Tom was tugging at a button-hole and looking sheepish.
Two thousand verses is a great many -... <Read More>
Tom's mouth watered for the apple, but... <Read More>

CONSTRAINTS:

The maximum length of a line in the input file is 300 characters. There cannot be more than one consequent space character in the input data.

My Code

#!/usr/bin/env ruby -w
def read_more(line)
  return line if line.size <= 55

  line = line[0...40]
  last_space_idx = line.rindex(' ')
  line = line[0...last_space_idx] if last_space_idx
  line + '... <Read More>'
end

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