Nairuby Ruby Challenge 8th Dec, 2016

README.md

Beautiful Binary String

Alice has a binary string, B, of length n. She thinks a binary string is beautiful if and only if it doesn't contain the substring “010”.

In one step, Alice can change a 0 to a 1 (or vice-versa). Count and print the minimum number of steps needed to make Alice see the string as beautiful.

Input Format
The first line contains an integer, n (the length of binary string B).
The second line contains a single binary string, B, of length.

Constraint

• 1 <= n <= 100
• Each character in B E {0, 1}.

Output Format
Print the minimum number of steps needed to make the string beautiful.

Sample Input 0
7
0101010

Sample Output 0
2

Sample Input 1
5
01100

Sample Output 1
0

Sample Input 2
10
0100101010

Sample Output 2
3

solution.rb

# Arguments
# n => length of the binary string
# bs => binary string
def bbs(n, bs)
  index = 0
  step_counter = 0

  while n > index
    if bs[index] == '0'
      # Check if the following 2 are 10
      if "#{bs[index+1]}#{bs[index+2]}" == '10'
        step_counter += 1
        index += 3
      else
        index += 1 
      end
    else
      index += 1
    end
  end

  step_counter # return number of steps
end