Enhancing a Voting System in Ruby

Introduction

Welcome back to another exciting session where we learn about enhancing existing functionality without causing regressions. Today, our scenario involves designing a voting system . We'll start with the basic implementation of the voting system and gradually introduce additional elements of complexity.

Starter Task Review

In our initial task, we created a simple voting system in Ruby with a set of basic functionalities: register_candidate(candidate_id) : This method is used to add new candidates to our system. vote(timestamp, voter_id, candidate_id) : This method facilitates users casting their votes. Each vote is given a timestamp. get_votes(candidate_id) : This method retrieves the total number of votes for a given candidate. top_n_candidates(n) : We also want to add a leaderboard functionality to our system. This method returns the top n candidates sorted by the number of votes.

Initial Solution Development

Let's jump into the Ruby code and begin the implementation of our starter task. Here, we use Ruby's built-in Hash and Array as the core of our design. These collections allow us to have dynamic lists keyed based on candidate IDs and voter IDs, which will greatly simplify our design. Rubyclass VotingSystem def initialize @candidates = {} # Stores candidate_id as key and votes as value @voters = {} # Tracks each voter's voting history end def register_candidate(candidate_id) return false if @candidates.key?(candidate_id) # Candidate is already registered @candidates[candidate_id] = 0 # Initialize candidates with 0 votes true end def vote(timestamp, voter_id, candidate_id) return false unless @candidates.key?(candidate_id) # Return false if candidate is not registered voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] } voter_history[:votes] << candidate_id # Record the vote voter_history[:timestamps] << timestamp # Record the time of the vote @candidates[candidate_id] += 1 # Increment vote count for the candidate true end def get_votes(candidate_id) @candidates[candidate_id] || nil # Retrieve vote count for a candidate or nil if not found end def top_n_candidates(n) @candidates.sort_by { |_, votes| -votes } .take(n) .map { |candidate_id, _| candidate_id } # Return top n candidates based on votes end endclass VotingSystem def initialize @candidates = {} # Stores candidate_id as key and votes as value @voters = {} # Tracks each voter's voting history end def register_candidate(candidate_id) return false if @candidates.key?(candidate_id) # Candidate is already registered @candidates[candidate_id] = 0 # Initialize candidates with 0 votes true end def vote(timestamp, voter_id, candidate_id) return false unless @candidates.key?(candidate_id) # Return false if candidate is not registered voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] } voter_history[:votes] << candidate_id # Record the vote voter_history[:timestamps] << timestamp # Record the time of the vote @candidates[candidate_id] += 1 # Increment vote count for the candidate true end def get_votes(candidate_id) @candidates[candidate_id] || nil # Retrieve vote count for a candidate or nil if not found end def top_n_candidates(n) @candidates.sort_by { |_, votes| -votes } .take(n) .map { |candidate_id, _| candidate_id } # Return top n candidates based on votes end end

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Ruby

class VotingSystem
  def initialize
    @candidates = {}  # Stores candidate_id as key and votes as value
    @voters = {}  # Tracks each voter's voting history
  end

  def register_candidate(candidate_id)
    return false if @candidates.key?(candidate_id)  # Candidate is already registered
    
    @candidates[candidate_id] = 0  # Initialize candidates with 0 votes
    true
  end

  def vote(timestamp, voter_id, candidate_id)
    return false unless @candidates.key?(candidate_id)  # Return false if candidate is not registered
    
    voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] }
    voter_history[:votes] << candidate_id  # Record the vote
    voter_history[:timestamps] << timestamp  # Record the time of the vote
    @candidates[candidate_id] += 1  # Increment vote count for the candidate
    true
  end

  def get_votes(candidate_id)
    @candidates[candidate_id] || nil  # Retrieve vote count for a candidate or nil if not found
  end

  def top_n_candidates(n)
    @candidates.sort_by { |_, votes| -votes }
               .take(n)
               .map { |candidate_id, _| candidate_id }  # Return top n candidates based on votes
  end
end

Ruby

class VotingSystem
  def initialize
    @candidates = {}
    @voters = {}
    @block_time = nil  # Records the timestamp after which no registration is allowed
  end

  def get_voting_history(voter_id)
    return nil unless @voters.key?(voter_id)

    voter_history = @voters[voter_id]
    voting_history = Hash.new(0)

    voter_history[:votes].each do |candidate_id|
      voting_history[candidate_id] += 1
    end
    
    voting_history  # Returns a hash with each candidate voted for and the number of times they were voted for
  end

  def block_voter_registration(timestamp)
    @block_time = timestamp  # Records the timestamp after which no registration is allowed
    true
  end
end

class VotingSystem
  def initialize
    @candidates = {}
    @voters = {}
    @block_time = nil  # Records the timestamp after which no registration is allowed
  end

  def get_voting_history(voter_id)
    return nil unless @voters.key?(voter_id)

    voter_history = @voters[voter_id]
    voting_history = Hash.new(0)

    voter_history[:votes].each do |candidate_id|
      voting_history[candidate_id] += 1
    end
    
    voting_history  # Returns a hash with each candidate voted for and the number of times they were voted for
  end

  def block_voter_registration(timestamp)
    @block_time = timestamp  # Records the timestamp after which no registration is allowed
    true
  end
end

Ruby

class VotingSystem
  def vote(timestamp, voter_id, candidate_id)
    # Check if block_time is set and if the vote attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time
    
    return false unless @candidates.key?(candidate_id)  # Return false if the candidate is not registered
    
    voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] }
    voter_history[:votes] << candidate_id  # Record the vote
    voter_history[:timestamps] << timestamp  # Record the time of the vote
    @candidates[candidate_id] += 1  # Increment vote count for the candidate
    
    true
  end
end

class VotingSystem
  def vote(timestamp, voter_id, candidate_id)
    # Check if block_time is set and if the vote attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time
    
    return false unless @candidates.key?(candidate_id)  # Return false if the candidate is not registered
    
    voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] }
    voter_history[:votes] << candidate_id  # Record the vote
    voter_history[:timestamps] << timestamp  # Record the time of the vote
    @candidates[candidate_id] += 1  # Increment vote count for the candidate
    
    true
  end
end

Ruby

class VotingSystem
  def change_vote(timestamp, voter_id, old_candidate_id, new_candidate_id)
    # Check if block_time is set and if the vote change attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time

    # Verify existence in the voting system
    return false unless @candidates.key?(old_candidate_id) && @candidates.key?(new_candidate_id)
    
    voter_history = @voters[voter_id]
    return false unless voter_history && voter_history[:votes].include?(old_candidate_id)

    # Confirm voter has voted for the old candidate
    last_vote_index = voter_history[:votes].rindex(old_candidate_id)
    return false unless last_vote_index

    # Ensure the operation is within the permitted timeframe
    return false if timestamp - voter_history[:timestamps][last_vote_index] > 86400  # 24 hours in seconds

    # Perform the vote change
    # Remove the old vote
    voter_history[:votes][last_vote_index] = new_candidate_id
    voter_history[:timestamps][last_vote_index] = timestamp

    # Update candidates' vote counts
    @candidates[old_candidate_id] -= 1
    @candidates[new_candidate_id] += 1

    true
  end
end

class VotingSystem
  def change_vote(timestamp, voter_id, old_candidate_id, new_candidate_id)
    # Check if block_time is set and if the vote change attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time

    # Verify existence in the voting system
    return false unless @candidates.key?(old_candidate_id) && @candidates.key?(new_candidate_id)
    
    voter_history = @voters[voter_id]
    return false unless voter_history && voter_history[:votes].include?(old_candidate_id)

    # Confirm voter has voted for the old candidate
    last_vote_index = voter_history[:votes].rindex(old_candidate_id)
    return false unless last_vote_index

    # Ensure the operation is within the permitted timeframe
    return false if timestamp - voter_history[:timestamps][last_vote_index] > 86400  # 24 hours in seconds

    # Perform the vote change
    # Remove the old vote
    voter_history[:votes][last_vote_index] = new_candidate_id
    voter_history[:timestamps][last_vote_index] = timestamp

    # Update candidates' vote counts
    @candidates[old_candidate_id] -= 1
    @candidates[new_candidate_id] += 1

    true
  end
end

Ruby

class VotingSystem
  def initialize
    @candidates = {}
    @voters = {}
    @block_time = nil  # Records the timestamp after which no registration is allowed
  end

  def get_voting_history(voter_id)
    return nil unless @voters.key?(voter_id)

    voter_history = @voters[voter_id]
    voting_history = Hash.new(0)

    voter_history[:votes].each do |candidate_id|
      voting_history[candidate_id] += 1
    end
    
    voting_history  # Returns a hash with each candidate voted for and the number of times they were voted for
  end

  def block_voter_registration(timestamp)
    @block_time = timestamp  # Records the timestamp after which no registration is allowed
    true
  end
end

Ruby

class VotingSystem
  def vote(timestamp, voter_id, candidate_id)
    # Check if block_time is set and if the vote attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time
    
    return false unless @candidates.key?(candidate_id)  # Return false if the candidate is not registered
    
    voter_history = @voters[voter_id] ||= { votes: [], timestamps: [] }
    voter_history[:votes] << candidate_id  # Record the vote
    voter_history[:timestamps] << timestamp  # Record the time of the vote
    @candidates[candidate_id] += 1  # Increment vote count for the candidate
    
    true
  end
end

Ruby

class VotingSystem
  def change_vote(timestamp, voter_id, old_candidate_id, new_candidate_id)
    # Check if block_time is set and if the vote change attempt is after the block timestamp
    return false if @block_time && timestamp >= @block_time

    # Verify existence in the voting system
    return false unless @candidates.key?(old_candidate_id) && @candidates.key?(new_candidate_id)
    
    voter_history = @voters[voter_id]
    return false unless voter_history && voter_history[:votes].include?(old_candidate_id)

    # Confirm voter has voted for the old candidate
    last_vote_index = voter_history[:votes].rindex(old_candidate_id)
    return false unless last_vote_index

    # Ensure the operation is within the permitted timeframe
    return false if timestamp - voter_history[:timestamps][last_vote_index] > 86400  # 24 hours in seconds

    # Perform the vote change
    # Remove the old vote
    voter_history[:votes][last_vote_index] = new_candidate_id
    voter_history[:timestamps][last_vote_index] = timestamp

    # Update candidates' vote counts
    @candidates[old_candidate_id] -= 1
    @candidates[new_candidate_id] += 1

    true
  end
end

Introduction

Starter Task Review

Initial Solution Development

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Introduce New Methods

Implementing New Methods: get_voting_history and block_voter_registration

Updating the vote Method

Implementing change_vote Method

Lesson Summary