valid-tic-tac-toe-state

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Algorithms

Given a Tic-Tac-Toe board as a string array <code>board</code>, return <code>true</code> 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 <code>3 x 3</code> array that consists of characters <code>&#39; &#39;</code>, <code>&#39;X&#39;</code>, and <code>&#39;O&#39;</code>. The <code>&#39; &#39;</code> character represents an empty square.

Here are the rules of Tic-Tac-Toe:

<ul>
	<li>Players take turns placing characters into empty squares <code>&#39; &#39;</code>.</li>
	<li>The first player always places <code>&#39;X&#39;</code> characters, while the second player always places <code>&#39;O&#39;</code> characters.</li>
	<li><code>&#39;X&#39;</code> and <code>&#39;O&#39;</code> characters are always placed into empty squares, never filled ones.</li>
	<li>The game ends when there are three of the same (non-empty) character filling any row, column, or diagonal.</li>
	<li>The game also ends if all squares are non-empty.</li>
	<li>No more moves can be played if the game is over.</li>
</ul>

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe1-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
Input: board = [&quot;O &quot;,&quot; &quot;,&quot; &quot;]
Output: false
Explanation: The first player always plays &quot;X&quot;.
</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe2-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
Input: board = [&quot;XOX&quot;,&quot; X &quot;,&quot; &quot;]
Output: false
Explanation: Players take turns making moves.
</pre>

Example 3:
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe4-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
Input: board = [&quot;XOX&quot;,&quot;O O&quot;,&quot;XOX&quot;]
Output: true
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>board.length == 3</code></li>
	<li><code>board[i].length == 3</code></li>
	<li><code>board[i][j]</code> is either <code>&#39;X&#39;</code>, <code>&#39;O&#39;</code>, or <code>&#39; &#39;</code>.</li>
</ul>

validTicTacToe

Valid Tic-Tac-Toe State

Design Tic-Tac-Toe

design-tic-tac-toe

设计井字棋

Array

Matrix

给你一个字符串数组 <code>board</code> 表示井字游戏的棋盘。当且仅当在井字游戏过程中，棋盘有可能达到 <code>board</code> 所显示的状态时，才返回 <code>true</code> 。

井字游戏的棋盘是一个 <code>3 x 3</code> 数组，由字符 <code>' '</code>，<code>'X'</code> 和 <code>'O'</code> 组成。字符 <code>' '</code> 代表一个空位。

以下是井字游戏的规则：

<ul>
	<li>玩家轮流将字符放入空位（<code>' '</code>）中。</li>
	<li>玩家 1 总是放字符 <code>'X'</code> ，而玩家 2 总是放字符 <code>'O'</code> 。</li>
	<li><code>'X'</code> 和 <code>'O'</code> 只允许放置在空位中，不允许对已放有字符的位置进行填充。</li>
	<li>当有 3 个相同（且非空）的字符填充任何行、列或对角线时，游戏结束。</li>
	<li>当所有位置非空时，也算为游戏结束。</li>
	<li>如果游戏结束，玩家不允许再放置字符。</li>
</ul>

&nbsp;

示例 1：
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe1-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
输入：board = ["O "," "," "]
输出：false
解释：玩家 1 总是放字符 "X" 。
</pre>

示例 2：
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe2-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
输入：board = ["XOX"," X "," "]
输出：false
解释：玩家应该轮流放字符。
</pre>

示例 3:
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/15/tictactoe4-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
输入：board = ["XOX","O O","XOX"]
输出：true
</pre>

&nbsp;

提示：

<ul>
	<li><code>board.length == 3</code></li>
	<li><code>board[i].length == 3</code></li>
	<li><code>board[i][j]</code> 为 <code>'X'</code>、<code>'O'</code> 或 <code>' '</code></li>
</ul>