Answers and hints¶

These functions work with a player’s answer, complete or partial. They are the pieces of a puzzle app: check what the player has entered, and suggest the next step.

Answers¶

An answer is a Solution: pp.Solution(genre, cells), with cells as a tuple of rows. The values depend on the genre:

Genre	Cell values
Sudoku, fillomino	Numbers, 0 for unmarked
Kakuro	Digits, 0 for unmarked, `None` for a block
Nurikabe, hitori, kakurasu	`pp.Mark.SHADED`, `pp.Mark.UNSHADED` or `pp.Mark.UNMARKED`
Hashi	Text: `"."` for water, the island number, `"-"` or `"="` for one or two horizontal bridges, `"\|"` or `"H"` for one or two vertical bridges

The answer must have the puzzle’s genre and shape. Solutions from solve and generate use the same form, so a solution is also a complete answer.

puzzle = pp.Puzzle.from_id('sudoku:4x4:31............34')
answer = pp.Solution("sudoku", ((3, 1, 4, 0),
                                (0, 0, 0, 0),
                                (0, 0, 0, 0),
                                (0, 0, 3, 4)))

Checking¶

check(puzzle, answer) returns a list of Violations, one for each rule the answer breaks. The list is empty when it breaks none.

>>> wrong = pp.Solution("sudoku", ((3, 1, 3, 0), (0, 0, 0, 0), (0, 0, 0, 0), (0, 0, 3, 4)))
>>> pp.check(puzzle, wrong)
[Violation(rule=1, place={'row': 0}, values={'filled': 3, 'size': 4}), Violation(rule=2, place={'col': 2}, values={'filled': 2, 'size': 4})]

Each Violation has:

Field	Value
`rule`	The rule’s number on the genre page, such as R1
`place`	Where: a row, a column, a cell or another part of the grid
`values`	The numbers involved

check compares the answer with the rules, not with the solution. An answer can break no rule and still be wrong; compare it with pp.solve(puzzle) to find that out.

Unmarked cells¶

Unmarked cells break no rule, so a partial answer only reports what is already wrong. With finished=True, unmarked cells and undrawn bridges first take the genre’s default for a finished answer, such as unshaded or no bridge. The result then also reports what is still missing:

>>> pp.check(puzzle, answer)
[]
>>> len(pp.check(puzzle, answer, finished=True))
12

Hints¶

hint(puzzle, answer=None) returns the next Step a solver would take from the answer, or None when the answer is already solved. Without an answer, it starts from the clues.

>>> pp.hint(puzzle, answer)
Step(level=<Difficulty.EASY: 'easy'>, technique='hidden_single', removed=((1, 2, '2'), (1, 3, '2'), (2, 3, '2')))

A Step has:

Field	Value
`level`	The level of the technique
`technique`	The technique’s name, as listed on the genre page
`removed`	The candidates the step rules out

Each item in removed is (row, col, value) for a cell, or (row, col, row2, col2, value) for the bridges between two hashi islands. Rows and columns count from 0.