My solution of Google codegem 2017 - Problem A. Oversized Pancake Flipper

problem_a.rb

def flip(string, fliper_size, flip_at)
  i = 0
  if (flip_at + fliper_size) <= string.length 
    while i < fliper_size
      if string[flip_at + i] == '-'
        string[flip_at + i] = '+'
      elsif string[flip_at + i] = '+'
        string[flip_at + i] = '-'
      end
      i += 1
    end
  end
  return string
end


line_num = 0
fliper_size = 0
num_of_row = 0
text=File.open('A-large-practice.in').read
text.gsub!(/\r\n?/, "\n")

text.each_line.with_index do |line, index|
  if index ==0 
    num_of_row = line
  else
    num_of_flip = 0
    array = line.chomp.split(' ', 2)
    line = array[0]
    fliper_size = array[1]
    i = 0
    while i < line.length
      if line[i] == '-'
        line = flip(line, fliper_size.to_i, i)
        num_of_flip += 1
      end
      i += 1
    end
    if line.include? '-'
      open('output.txt', "a") { |f| f << "Case ##{index}: IMPOSSIBLE\n" } 
    else
      open('output.txt', "a") { |f| f << "Case ##{index}: #{num_of_flip}\n" } 
    end
  end
end