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Java-based LeetCode algorithm problem solutions, regularly updated
782\. Transform to Chessboard
Hard
You are given an `n x n` binary grid `board`. In each move, you can swap any two rows with each other, or any two columns with each other.
Return _the minimum number of moves to transform the board into a **chessboard board**_. If the task is impossible, return `-1`.
A **chessboard board** is a board where no `0`'s and no `1`'s are 4-directionally adjacent.
**Example 1:**
![](https://assets.leetcode.com/uploads/2021/06/29/chessboard1-grid.jpg)
**Input:** board = [[0,1,1,0],[0,1,1,0],[1,0,0,1],[1,0,0,1]]
**Output:** 2
**Explanation:**
One potential sequence of moves is shown.
The first move swaps the first and second column.
The second move swaps the second and third row.
**Example 2:**
![](https://assets.leetcode.com/uploads/2021/06/29/chessboard2-grid.jpg)
**Input:** board = [[0,1],[1,0]]
**Output:** 0
**Explanation:** Also note that the board with 0 in the top left corner, is also a valid chessboard.
**Example 3:**
![](https://assets.leetcode.com/uploads/2021/06/29/chessboard3-grid.jpg)
**Input:** board = [[1,0],[1,0]]
**Output:** -1
**Explanation:** No matter what sequence of moves you make, you cannot end with a valid chessboard.
**Constraints:**
* `n == board.length`
* `n == board[i].length`
* `2 <= n <= 30`
* `board[i][j]` is either `0` or `1`.