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

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

    Solution :

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

    Niveau : 3  (masque 56)
    Etude  : 20 sudoku(s)
    Debut  : Sat Dec 15 16:11:50 2018
    Fin    : Sat Dec 15 16:11:50 2018
    (c)2006 resoo.org