The Australian Electoral Commission (AEC) Online Voting System requires the following computations:

• Pre-populate its system with registered voters from an existing data source
• Allow users to sign-up using an unique email address
• Let voters rank a pre-determined list of candidates
• Calculate live tallies of the results so far
• Determine the overall winner of an election

Algorithm: step-by-step procedures required to solve a problem.

Pseudocode: a type of descriptive algorithm that is a mixture of everyday language and programming languages.

more_algorithms.pdf

BEGIN launch(prereg_voters)
  IF election_event_name UNDEFINED THEN
    INPUT GLOBAL election_event_name
  ENDIF
  IF election_event_candidates UNDEFINED THEN
    SET GLOBAL election_event_candidates TO {}
    WHILE INPUT candidate_name
      SET candidate {
        name: candidate_name, 
        result: {
          rank: 0
        }
      } 
      APPEND candidate TO election_event_candidates
    ENDWHILE
  ENDIF  
  IF voter_list UNDEFINED THEN
    SET GLOBAL voter_list TO []
  ENDIF
  
  #populate existing voter list into application data structure:
  
  IF prereg_voters DEFINED THEN
    FOR each_voter IN prereg_voters:
      SET voter {
        email: prereg_voters[email],
        pword: prereg_voters[password],
        election: [{
          event: election_event_name,
          votes: []
        }],
      }
      APPEND voter TO voter_list
    ENDFOR
  ENDIF
END launch()

BEGIN register()
  INPUT new_email
  INPUT new_password
  SET existing_voter TO false
  FOR registered_voter IN voter_list:
    IF registered_voter[email] == new_email THEN
      SET existing_voter TO true
    ENDIF
  ENDFOR
  IF NOT existing_voter THEN
    SET voter {
      email: new_email,
      pword: new_password,
      election: [{
        event: election_event_name,
        votes: []
      }],
    }
    APPEND voter TO voter_list
  ENDIF
END register()

BEGIN authenticate()
  INPUT login_attempt_email
  INPUT login_attempt_password
  SET authenticated_voter TO NULL
  FOR registered_voter IN voter_list:
    IF registered_voter[email] == login_attempt_email THEN
      IF registered_voter[pword] == login_attempt_password THEN
        SET authenticated_voter TO registered_voter
      ENDIF
    ENDIF
  ENDFOR
  RETURN authenticated_voter
END authenticate()

BEGIN voting()
  INPUT close_voting_timedate
  SET now_timedate TO SYSTEM.TIME
  WHILE now_timedate < close_voting_timedate
    voter = authenticate()
    IF voter IS NOT NULL THEN
      FOR candidate IN election_event_candidates:
        INPUT preference_ranking
        SET voter[election][votes][preference_ranking] TO candidate[name]
      ENDFOR
    ENDIF
    SET now_timedate TO SYSTEM.TIME
  END WHILE
END voting()

BEGIN tally_votes()
  FOR vote IN voter_list:
    FOR preference IN RANGE(LENGTH OF election_event_candidates):
      SET chosen_candidate TO vote[election][votes][preference]
      INCREASE election_event_candidates[chosen_candidate][result][rank] BY preference
    ENDFOR
  ENDFOR
END tally_votes()

BEGIN determine_winner()
  #set first candidate as default leader on initial run:
  SET leading_candidate TO election_event_candidates[0][name]
  SET leading_rank TO election_event_candidates[0][result][rank]
  FOR candidate IN election_event_candidates:
    IF candidate[result][rank] > leading_rank THEN
      SET leading_candidate TO candidate[name]
    ENDIF
  ENDFOR
  RETURN leading_candidate
END determine_winner()