SumString.rb

=begin

Given a random string consisting of numbers, letters, symbols, you need
to sum up the numbers in the string.

Note:

Consecutive integers should be treated as a single number. eg, 2015 should
be treated as a single number 2015, NOT four numbers
All the numbers should be treaded as positive integer.
eg, 11-14 should be treated as two numbers 11 and 14. Same as 3.14,
should be treated as two numbers 3 and 14
If no number was given in the string, it should return 0
Example:

str = "In 2015, I want to know how much does iPhone 6+ cost?"
The numbers are 2015, 6

Sum is 2021.

=end

# My Solution
def sum_from_string(str)
  num = ""
  sum = 0
  str.split("").each_with_index do |l,i|
    if l =~ /[0-9]/
      num += l
      if str[i+1] =~ /[0-9]/
      else
        sum += num.to_i
        num = ""
      end
    end
  end
  sum
end

# Better Solution
def sum_from_string(str)
  str.scan(/\d+/).map(&:to_i).reduce(0, :+)
end

# Another Solution
def sum_from_string(str)
  str.scan(/\d+/).map(&:to_i).inject(:+) || 0
end