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212cdfe36c
* Added algorithm to deeply clone a graph * Fixed file name and removed a function call * Removed nested function and fixed class parameter types * Fixed doctests * bug fix * Added class decorator * Updated doctests and fixed precommit errors * Cleaned up code * Simplified doctest * Added doctests * Code simplification * Created function which validates sudoku boards * Update matrix/validate_sudoku_board.py * Fixed precommit errors * Removed file accidentally included * Improved readability and simplicity * Add timeit benchmarks * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Update validate_sudoku_board.py --------- Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
108 lines
3.4 KiB
Python
108 lines
3.4 KiB
Python
"""
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LeetCode 36. Valid Sudoku
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https://leetcode.com/problems/valid-sudoku/
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https://en.wikipedia.org/wiki/Sudoku
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Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be
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validated according to the following rules:
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- Each row must contain the digits 1-9 without repetition.
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- Each column must contain the digits 1-9 without repetition.
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- Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9
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without repetition.
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Note:
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A Sudoku board (partially filled) could be valid but is not necessarily
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solvable.
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Only the filled cells need to be validated according to the mentioned rules.
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"""
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from collections import defaultdict
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NUM_SQUARES = 9
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EMPTY_CELL = "."
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def is_valid_sudoku_board(sudoku_board: list[list[str]]) -> bool:
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"""
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This function validates (but does not solve) a sudoku board.
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The board may be valid but unsolvable.
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>>> is_valid_sudoku_board([
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... ["5","3",".",".","7",".",".",".","."]
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... ,["6",".",".","1","9","5",".",".","."]
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... ,[".","9","8",".",".",".",".","6","."]
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... ,["8",".",".",".","6",".",".",".","3"]
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... ,["4",".",".","8",".","3",".",".","1"]
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... ,["7",".",".",".","2",".",".",".","6"]
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... ,[".","6",".",".",".",".","2","8","."]
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... ,[".",".",".","4","1","9",".",".","5"]
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... ,[".",".",".",".","8",".",".","7","9"]
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... ])
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True
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>>> is_valid_sudoku_board([
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... ["8","3",".",".","7",".",".",".","."]
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... ,["6",".",".","1","9","5",".",".","."]
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... ,[".","9","8",".",".",".",".","6","."]
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... ,["8",".",".",".","6",".",".",".","3"]
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... ,["4",".",".","8",".","3",".",".","1"]
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... ,["7",".",".",".","2",".",".",".","6"]
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... ,[".","6",".",".",".",".","2","8","."]
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... ,[".",".",".","4","1","9",".",".","5"]
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... ,[".",".",".",".","8",".",".","7","9"]
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... ])
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False
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>>> is_valid_sudoku_board([["1", "2", "3", "4", "5", "6", "7", "8", "9"]])
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Traceback (most recent call last):
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...
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ValueError: Sudoku boards must be 9x9 squares.
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>>> is_valid_sudoku_board(
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... [["1"], ["2"], ["3"], ["4"], ["5"], ["6"], ["7"], ["8"], ["9"]]
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... )
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Traceback (most recent call last):
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...
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ValueError: Sudoku boards must be 9x9 squares.
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"""
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if len(sudoku_board) != NUM_SQUARES or (
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any(len(row) != NUM_SQUARES for row in sudoku_board)
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):
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error_message = f"Sudoku boards must be {NUM_SQUARES}x{NUM_SQUARES} squares."
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raise ValueError(error_message)
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row_values: defaultdict[int, set[str]] = defaultdict(set)
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col_values: defaultdict[int, set[str]] = defaultdict(set)
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box_values: defaultdict[tuple[int, int], set[str]] = defaultdict(set)
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for row in range(NUM_SQUARES):
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for col in range(NUM_SQUARES):
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value = sudoku_board[row][col]
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if value == EMPTY_CELL:
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continue
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box = (row // 3, col // 3)
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if (
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value in row_values[row]
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or value in col_values[col]
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or value in box_values[box]
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):
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return False
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row_values[row].add(value)
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col_values[col].add(value)
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box_values[box].add(value)
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return True
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if __name__ == "__main__":
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from doctest import testmod
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from timeit import timeit
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testmod()
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print(timeit("is_valid_sudoku_board(valid_board)", globals=globals()))
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print(timeit("is_valid_sudoku_board(invalid_board)", globals=globals()))
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