SudokuPerl !
    [ http://www.resoo.org/sudoku ]

    +===+===+===++===+===+===++===+===+===+
    |   |   | 2 ||   |   |   || 6 |   |   |
    +---+---+---++---+---+---++---+---+---+
    | 4 |   |   ||   |   |   ||   | 1 |   |
    +---+---+---++---+---+---++---+---+---+
    | 5 |   | 7 || 6 |   | 3 ||   |   |   |
    +===+===+===++===+===+===++===+===+===+
    |   |   |   || 1 |   | 9 ||   | 5 |   |
    +---+---+---++---+---+---++---+---+---+
    |   |   |   ||   |   | 4 || 3 |   |   |
    +---+---+---++---+---+---++---+---+---+
    | 8 |   |   ||   |   |   ||   | 6 |   |
    +===+===+===++===+===+===++===+===+===+
    |   | 4 |   ||   | 3 |   || 8 | 2 |   |
    +---+---+---++---+---+---++---+---+---+
    |   | 9 |   ||   | 8 |   ||   |   | 7 |
    +---+---+---++---+---+---++---+---+---+
    | 7 |   | 8 || 4 |   |   ||   |   |   |
    +===+===+===++===+===+===++===+===+===+
    

    Solution :

    +===+===+===++===+===+===++===+===+===+
    | 9 | 8 | 2 || 7 | 5 | 1 || 6 | 3 | 4 |
    +---+---+---++---+---+---++---+---+---+
    | 4 | 3 | 6 || 2 | 9 | 8 || 7 | 1 | 5 |
    +---+---+---++---+---+---++---+---+---+
    | 5 | 1 | 7 || 6 | 4 | 3 || 9 | 8 | 2 |
    +===+===+===++===+===+===++===+===+===+
    | 3 | 6 | 4 || 1 | 7 | 9 || 2 | 5 | 8 |
    +---+---+---++---+---+---++---+---+---+
    | 2 | 5 | 9 || 8 | 6 | 4 || 3 | 7 | 1 |
    +---+---+---++---+---+---++---+---+---+
    | 8 | 7 | 1 || 3 | 2 | 5 || 4 | 6 | 9 |
    +===+===+===++===+===+===++===+===+===+
    | 1 | 4 | 5 || 9 | 3 | 7 || 8 | 2 | 6 |
    +---+---+---++---+---+---++---+---+---+
    | 6 | 9 | 3 || 5 | 8 | 2 || 1 | 4 | 7 |
    +---+---+---++---+---+---++---+---+---+
    | 7 | 2 | 8 || 4 | 1 | 6 || 5 | 9 | 3 |
    +===+===+===++===+===+===++===+===+===+
    

    Niveau : 3  (masque 56)
    Etude  : 50 sudoku(s)
    Debut  : Thu Jul  2 11:04:14 2020
    Fin    : Thu Jul  2 11:04:14 2020
    (c)2006 resoo.org