目标
给你一个下标从 0 开始的 8 x 8 网格 board ，其中 board[r][c] 表示游戏棋盘上的格子 (r, c) 。棋盘上空格用 '.' 表示，白色格子用 'W' 表示，黑色格子用 'B' 表示。
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，合法 操作必须满足：涂色后这个格子是 好线段的一个端点 （好线段可以是水平的，竖直的或者是对角线）。
好线段 指的是一个包含 三个或者更多格子（包含端点格子）的线段，线段两个端点格子为 同一种颜色 ，且中间剩余格子的颜色都为 另一种颜色 （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：
给你两个整数 rMove 和 cMove 以及一个字符 color ，表示你正在执行操作的颜色（白或者黑），如果将格子 (rMove, cMove) 变成颜色 color 后，是一个 合法 操作，那么返回 true ，如果不是合法操作返回 false 。
示例 1：
输入：board = [[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],["W","B","B",".","W","W","W","B"],[".",".",".","B",".",".",".","."],[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."]], rMove = 4, cMove = 3, color = "B"
输出：true
解释：'.'，'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。示例 2：
输入：board = [[".",".",".",".",".",".",".","."],[".","B",".",".","W",".",".","."],[".",".","W",".",".",".",".","."],[".",".",".","W","B",".",".","."],[".",".",".",".",".",".",".","."],[".",".",".",".","B","W",".","."],[".",".",".",".",".",".","W","."],[".",".",".",".",".",".",".","B"]], rMove = 4, cMove = 4, color = "W"
输出：false
解释：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。说明：
- board.length == board[r].length == 8
- 0 <= rMove, cMove < 8
board[rMove][cMove] == '.'- color 要么是 'B' 要么是 'W' 。
思路
有一个 8 x 8 网格，网格中 . 表示空格，W 表示白色，B 表示黑色。现在需要给空格涂色，合法的操作指涂色的格子是好线段的端点。好线段长度至少包含三个格子，且两端颜色一致，中间颜色也一致但与两端颜色不同。给定一个操作，判断其是否合法。
按照题意从涂色端点开始依次遍历八个方向上是否存在好线段。
代码
/**
* @date 2024-07-07 12:21
*/
public class CheckMove1958 {
public boolean checkMove(char[][] board, int rMove, int cMove, char color) {
if (board[rMove][cMove] != '.') {
return false;
}
int[][] direction = new int[][]{
{-1, 0}, {-1, 1}, {0, 1}, {1, 1}, {1, 0}, {1, -1}, {0, -1}, {-1, -1}
};
char opposite = (char) (color ^ 'B' ^ 'W');
for (int[] d : direction) {
int cnt = 0;
int r = d[0];
int c = d[1];
while (rMove + r >= 0 && rMove + r < 8
&& cMove + c >= 0 && cMove + c < 8
&& board[rMove + r][cMove + c] == opposite) {
r += d[0];
c += d[1];
cnt++;
}
// 题目要求至少三个格子，所以要求cnt>0
if (cnt > 0 && rMove + r >= 0 && rMove + r < 8
&& cMove + c >= 0 && cMove + c < 8
&& board[rMove + r][cMove + c] == color) {
return true;
}
}
return false;
}
}
性能
