Leetcode: Transform to Chessboard

Transform to Chessboard

Similar Problems:

An N x N board contains only 0s and 1s. In each move, you can swap any 2 rows with each other, or any 2 columns with each other.

What is the minimum number of moves to transform the board into a “chessboard” – a board where no 0s and no 1s are 4-directionally adjacent? If the task is impossible, return -1.


Input: board = [[0,1,1,0],[0,1,1,0],[1,0,0,1],[1,0,0,1]]
Output: 2
One potential sequence of moves is shown below, from left to right:

0110     1010     1010
0110 --> 1010 --> 0101
1001     0101     1010
1001     0101     0101

The first move swaps the first and second column.
The second move swaps the second and third row.
Input: board = [[0, 1], [1, 0]]
Output: 0
Also note that the board with 0 in the top left corner,

is also a valid chessboard.
Input: board = [[1, 0], [1, 0]]
Output: -1
No matter what sequence of moves you make, you cannot end with a valid chessboard.


  • board will have the same number of rows and columns, a number in the range [2, 30].
  • board[i][j] will be only 0s or 1s.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

  • Solution: XXX
General Thinking:
// Blog link: https://code.dennyzhang.com/transform-to-chessboard


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