leetcode-problemset/leetcode-cn/problem (Chinese)/检查操作是否合法 [check-if-move-is-legal].html

<p>给你一个下标从&nbsp;<strong>0</strong>&nbsp;开始的&nbsp;<code>8 x 8</code> 网格&nbsp;<code>board</code>&nbsp;，其中&nbsp;<code>board[r][c]</code>&nbsp;表示游戏棋盘上的格子&nbsp;<code>(r, c)</code>&nbsp;。棋盘上空格用&nbsp;<code>'.'</code>&nbsp;表示，白色格子用&nbsp;<code>'W'</code>&nbsp;表示，黑色格子用&nbsp;<code>'B'</code>&nbsp;表示。</p>

<p>游戏中每次操作步骤为：选择一个空格子，将它变成你正在执行的颜色（要么白色，要么黑色）。但是，<strong>合法 </strong>操作必须满足：涂色后这个格子是 <strong>好线段的一个端点</strong>&nbsp;（好线段可以是水平的，竖直的或者是对角线）。</p>

<p><strong>好线段</strong>&nbsp;指的是一个包含 <strong>三个或者更多格子（包含端点格子）</strong>的线段，线段两个端点格子为 <strong>同一种颜色</strong>&nbsp;，且中间剩余格子的颜色都为 <strong>另一种颜色</strong>&nbsp;（线段上不能有任何空格子）。你可以在下图找到好线段的例子：</p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/22/goodlines5.png" style="width: 500px; height: 312px;" />
<p>给你两个整数&nbsp;<code>rMove</code> 和&nbsp;<code>cMove</code>&nbsp;以及一个字符&nbsp;<code>color</code>&nbsp;，表示你正在执行操作的颜色（白或者黑），如果将格子&nbsp;<code>(rMove, cMove)</code>&nbsp;变成颜色&nbsp;<code>color</code>&nbsp;后，是一个&nbsp;<strong>合法</strong>&nbsp;操作，那么返回&nbsp;<code>true</code>&nbsp;，如果不是合法操作返回&nbsp;<code>false</code>&nbsp;。</p>

<p>&nbsp;</p>

<p><strong>示例 1：</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid11.png" style="width: 350px; height: 350px;" /></p>

<pre>
<b>输入：</b>board = [[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],["W","B","B",".","W","W","W","B"],[".",".",".","B",".",".",".","."],[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."]], rMove = 4, cMove = 3, color = "B"
<b>输出：</b>true
<b>解释：</b>'.'，'W' 和 'B' 分别用颜色蓝色，白色和黑色表示。格子 (rMove, cMove) 用 'X' 标记。
以选中格子为端点的两个好线段在上图中用红色矩形标注出来了。
</pre>

<p><strong>示例 2：</strong></p>

<p><img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid2.png" style="width: 350px; height: 351px;" /></p>

<pre>
<b>输入：</b>board = [[".",".",".",".",".",".",".","."],[".","B",".",".","W",".",".","."],[".",".","W",".",".",".",".","."],[".",".",".","W","B",".",".","."],[".",".",".",".",".",".",".","."],[".",".",".",".","B","W",".","."],[".",".",".",".",".",".","W","."],[".",".",".",".",".",".",".","B"]], rMove = 4, cMove = 4, color = "W"
<b>输出：</b>false
<b>解释：</b>虽然选中格子涂色后，棋盘上产生了好线段，但选中格子是作为中间格子，没有产生以选中格子为端点的好线段。
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>board.length == board[r].length == 8</code></li>
	<li><code>0 &lt;= rMove, cMove &lt; 8</code></li>
	<li><code>board[rMove][cMove] == '.'</code></li>
	<li><code>color</code>&nbsp;要么是&nbsp;<code>'B'</code> 要么是&nbsp;<code>'W'</code>&nbsp;。</li>
</ul>