Einstein riddle solver in Python, for Skillshare student question

einstein_riddle.py

finalized = [{}, {}, {}, {}, {}] # 5 houses, with no properties set yet

# 1. express all constraints
constraints = [
  [{'nationality': 'Brit', 'color': 'red'}], # the Brit lives in the red house
  [{'drink': 'coffee', 'color': 'green', 'offset': 0}, {'color': white', 'offset': 1}],
  ...
]

# 2. iteratively...
while constraints: # if any constraints are left
  for constraint in constraints:
    possible_positions = get_possible_positions(finalized, constraint)
    if len(possible_positions) == 1:
      apply_constraint(finalized[possible_positions[0]], constraint)

einstein_riddle_helper.py

def get_possible_positions(finalized, constraint):
  """Collect all possible positions for this constraint's house to live in."""
  possible_positions = []
  for idx_house in range(len(finalized)):
    if is_possible_position(finalized, idx_house, constraint):
      possible_positions.append(i)
  return possible_positions

def is_possible_position(finalized, idx_start, constraint):
  """Check whether this is a valid starting position for all the houses specified in the constraint.

  In the 1-column case, check if this is a valid position for the 1-column constraint.
  """
  for column in constraint:
    idx_house = idx_start + column.get('offset', 0) # get the offset if it exists. If no offset key, use 0.
    if is_conflicting_constraint(finalized[idx_house], col):
      return False
  return True

def is_conflicting_constraint(col1, col2):
  """Check if these two columns can co-exist.

  - For example, if one specifies color and the other specifies, they can coexist.
  - However, if both specify nationality, they cannot co-exist.
  """
  for key in col1:
    if key in col2:
      return True
  return False