794. Valid Tic-Tac-Toe State
Description
Given a Tic-Tac-Toe board as a string array board
, return true
if and only if it is possible to reach this board position during the course of a valid tic-tac-toe game.
The board is a 3 x 3
array that consists of characters ' '
, 'X'
, and 'O'
. The ' '
character represents an empty square.
Here are the rules of Tic-Tac-Toe:
- Players take turns placing characters into empty squares
' '
. - The first player always places
'X'
characters, while the second player always places'O'
characters. 'X'
and'O'
characters are always placed into empty squares, never filled ones.- The game ends when there are three of the same (non-empty) character filling any row, column, or diagonal.
- The game also ends if all squares are non-empty.
- No more moves can be played if the game is over.
Example 1:
Input: board = ["O "," "," "] Output: false Explanation: The first player always plays "X".
Example 2:
Input: board = ["XOX"," X "," "] Output: false Explanation: Players take turns making moves.
Example 3:
Input: board = ["XOX","O O","XOX"] Output: true
Constraints:
board.length == 3
board[i].length == 3
board[i][j]
is either'X'
,'O'
, or' '
.
Solutions
Solution 1
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