README_EN.md

794. Valid Tic-Tac-Toe State

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Description

A Tic-Tac-Toe board is given 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, and 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 3 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 = ["XXX", "   ", "OOO"]

Output: false



Example 4:

Input: board = ["XOX", "O O", "XOX"]

Output: true

Note:

• board is a length-3 array of strings, where each string board[i] has length 3.
• Each board[i][j] is a character in the set {" ", "X", "O"}.

Solutions

Python3

Java

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