README.md

1958. 检查操作是否合法

English Version

题目描述

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。

 

提示：

• board.length == board[r].length == 8
• 0 <= rMove, cMove < 8
• board[rMove][cMove] == '.'
• color 要么是 'B' 要么是 'W' 。

解法

Python3

class Solution:
    def checkMove(
        self, board: List[List[str]], rMove: int, cMove: int, color: str
    ) -> bool:
        dirs = [(1, 0), (0, 1), (-1, 0), (0, -1), (1, 1), (1, -1), (-1, 1), (-1, -1)]
        n = 8
        for a, b in dirs:
            i, j = rMove, cMove
            t = 0
            while 0 <= i + a < n and 0 <= j + b < n:
                t += 1
                i, j = i + a, j + b
                if board[i][j] in ['.', color]:
                    break
            if board[i][j] == color and t > 1:
                return True
        return False

Java

class Solution {
    private static final int[][] DIRS
        = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
    private static final int N = 8;

    public boolean checkMove(char[][] board, int rMove, int cMove, char color) {
        for (int[] d : DIRS) {
            int i = rMove, j = cMove;
            int t = 0;
            int a = d[0], b = d[1];
            while (0 <= i + a && i + a < N && 0 <= j + b && j + b < N) {
                ++t;
                i += a;
                j += b;
                if (board[i][j] == '.' || board[i][j] == color) {
                    break;
                }
            }
            if (board[i][j] == color && t > 1) {
                return true;
            }
        }
        return false;
    }
}

C++

class Solution {
public:
    vector<vector<int>> dirs = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
    int n = 8;

    bool checkMove(vector<vector<char>>& board, int rMove, int cMove, char color) {
        for (auto& d : dirs) {
            int a = d[0], b = d[1];
            int i = rMove, j = cMove;
            int t = 0;
            while (0 <= i + a && i + a < n && 0 <= j + b && j + b < n) {
                ++t;
                i += a;
                j += b;
                if (board[i][j] == '.' || board[i][j] == color) break;
            }
            if (board[i][j] == color && t > 1) return true;
        }
        return false;
    }
};

Go

func checkMove(board [][]byte, rMove int, cMove int, color byte) bool {
	dirs := [8][2]int{{1, 0}, {0, 1}, {-1, 0}, {0, -1}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}}
	n := 8
	for _, d := range dirs {
		a, b := d[0], d[1]
		i, j := rMove, cMove
		t := 0
		for 0 <= i+a && i+a < n && 0 <= j+b && j+b < n {
			t++
			i += a
			j += b
			if board[i][j] == '.' || board[i][j] == color {
				break
			}
		}
		if board[i][j] == color && t > 1 {
			return true
		}
	}
	return false
}

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