SudokuSolver

Insert 0 as a placeholder.

Easy

  5 2 |     6 |                       3 5 2 | 4 7 6 | 1 8 9
1 6   | 9     |     4                 1 6 8 | 9 5 2 | 7 3 4
  4 9 | 8   3 | 6 2                   7 4 9 | 8 1 3 | 6 2 5
---------------------                 ---------------------
4     |       | 8                     4 2 5 | 6 9 7 | 8 1 3
  8 3 | 2   1 | 5 9        -------->  6 8 3 | 2 4 1 | 5 9 7
    1 |       |     2                 9 7 1 | 5 3 8 | 4 6 2
---------------------                 ---------------------
  9 7 | 3   5 | 2 4                   8 9 7 | 3 6 5 | 2 4 1
2     |     9 |   5 6                 2 1 4 | 7 8 9 | 3 5 6
      | 1     | 9 7                   5 3 6 | 1 2 4 | 9 7 8

Insert it as:

052006000
160900004
049803620
400000800
083201590
001000002
097305240
200009056
000100970

Medium

    7 | 8 6 1 |                       9 4 7 | 8 6 1 | 2 5 3
    8 |     3 |                       2 1 8 | 4 5 3 | 6 7 9
5 6   |   9   |   1                   5 6 3 | 7 9 2 | 8 1 4
---------------------                 ---------------------
1     |   7   |   8 5                 1 9 4 | 2 7 6 | 3 8 5
      | 3 4 5 |            -------->  7 8 2 | 3 4 5 | 9 6 1
6 3   |   1   |     7                 6 3 5 | 9 1 8 | 4 2 7
---------------------                 ---------------------
  5   |   2   |   9 8                 3 5 6 | 1 2 4 | 7 9 8
      | 6     | 5                     4 7 1 | 6 8 9 | 5 3 2
      | 5 3 7 | 1                     8 2 9 | 5 3 7 | 1 4 6

Insert it as:

007861000
008003000
560090010
100070085
000345000
630010007
050020098
000600500
000537100

Hard

      | 8   1 |                       2 3 7 | 8 4 1 | 5 6 9
      |       |   4 3                 1 8 6 | 7 9 5 | 2 4 3
5     |       |                       5 9 4 | 3 2 6 | 7 1 8
---------------------                 ---------------------
      |   7   | 8                     3 1 5 | 6 7 4 | 8 9 2
      |       | 1          -------->  4 6 9 | 5 8 2 | 1 3 7
  2   |   3   |                       7 2 8 | 1 3 9 | 4 5 6
---------------------                 ---------------------
6     |       |   7 5                 6 4 2 | 9 1 8 | 3 7 5
    3 | 4     |                       8 5 3 | 4 6 7 | 9 2 1
      | 2     | 6                     9 7 1 | 2 5 3 | 6 8 4

Insert it as:

000801000
000000043
500000000
000070800
000000100
020030000
600000075
003400000
000200600