# 782. Transform to Chessboard """ you are given an 'n 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 rwos to transform the board intoa 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 """ class Solution(object): def movesToChessboard(self, board): """ :type board: List[List[int]] :rtype: int """ n = len(board) if any( board[0][0] ^ board[i][0] ^ board[0][j] ^ board[i][j] for i in range(n) for j in range(n) ): return -1 if not n / 2 <= sum(board[0]) <= (n + 1) / 2: return -1 if not n / 2 <= sum(board[i][0] for i in range(n)) <= (n + 1) / 2: return -1 col = sum(board[0][i] == i % 2 for i in range(n)) row = sum(board[i][0] == i % 2 for i in range(n)) if n % 2: if col % 2: col = n - col if row % 2: row = n - row else: col = min(n - col, col) row = min(n - row, row) return (col + row) / 2 if __name__ == "__main__": obj = Solution() print( obj.movesToChessboard( board=[[0, 1, 1, 0], [0, 1, 1, 0], [1, 0, 0, 1], [1, 0, 0, 1]] ) ) print(obj.movesToChessboard(board=[[0, 1], [1, 0]])) print(obj.movesToChessboard(board=[[1, 0], [1, 0]]))