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g0701_0800.s0782_transform_to_chessboard.readme.md Maven / Gradle / Ivy

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`.