lc 529 Minesweeper

Let's play the minesweeper game!

You are given a 2D char matrix representing the game board. 'M' represents an unrevealed mine, 'E' represents an unrevealed empty square, 'B' represents a revealed blank square that has no adjacent (above, below, left, right, and all 4 diagonals) mines, digit ('1' to '8') represents how many mines are adjacent to this revealed square, and finally 'X' represents a revealed mine.

Now given the next click position (row and column indices) among all the unrevealed squares ('M' or 'E'), return the board after revealing this position according to the following rules:

If a mine ('M') is revealed, then the game is over - change it to

'X'.
If an empty square ('E') with no adjacent mines is revealed, then

change it to revealed blank ('B') and all of its adjacent unrevealed

squares should be revealed recursively.
If an empty square ('E') with at least one adjacent mine is

revealed, then change it to a digit ('1' to '8') representing the

number of adjacent mines.
Return the board when no more squares will be revealed.

Example 1:

Input: 

[['E', 'E', 'E', 'E', 'E'],

 ['E', 'E', 'M', 'E', 'E'],

 ['E', 'E', 'E', 'E', 'E'],

 ['E', 'E', 'E', 'E', 'E']]

Click : [3,0]

Output: 

[['B', '1', 'E', '1', 'B'],

 ['B', '1', 'M', '1', 'B'],

 ['B', '1', '1', '1', 'B'],

 ['B', 'B', 'B', 'B', 'B']]

Explanation:

Example 2:

Input: 

[['B', '1', 'E', '1', 'B'],

 ['B', '1', 'M', '1', 'B'],

 ['B', '1', '1', '1', 'B'],

 ['B', 'B', 'B', 'B', 'B']]

Click : [1,2]

Output: 

[['B', '1', 'E', '1', 'B'],

 ['B', '1', 'X', '1', 'B'],

 ['B', '1', '1', '1', 'B'],

 ['B', 'B', 'B', 'B', 'B']]

Explanation:

Note:

The range of the input matrix's height and width is [1,50].
The click position will only be an unrevealed square ('M' or 'E'),

which also means the input board contains at least one clickable

square.
The input board won't be a stage when game is over (some mines have

been revealed).
For simplicity, not mentioned rules should be ignored in this

problem.For example, you don't need to reveal all the unrevealed

mines when the game is over, consider any cases that you will win

the game or flag any squares.

递归 Accepted##

扫雷游戏，其实还挺简单的，注意判断是否在版图之内，利用递归不断推算并且更新。

class Solution {

public:

    vector<vector<char>> updateBoard(vector<vector<char>>& board, vector<int>& click) {

        if (board[click[0]][click[1]] == 'M') {

            board[click[0]][click[1]] = 'X';

            return board;

        }

        reveal(board, click[0], click[1]);

        return board;

    }

    int out(vector<vector<char>>& board, int x, int y) {

        return (x < 0 || y < 0 || x >= board.size() || y >= board[0].size());

    }

    void reveal(vector<vector<char>>& board, int x, int y) {

        if (out(board, x, y))   return;

        if (board[x][y] == 'E') {

            int m = 0;

            if (!out(board, x-1, y-1) && board[x-1][y-1] == 'M') m++;

            if (!out(board, x-1, y) && board[x-1][y] == 'M') m++;

            if (!out(board, x-1, y+1) && board[x-1][y+1] == 'M') m++;

            if (!out(board, x, y-1) && board[x][y-1] == 'M') m++;

            if (!out(board, x, y+1) && board[x][y+1] == 'M') m++;

            if (!out(board, x+1, y-1) && board[x+1][y-1] == 'M') m++;

            if (!out(board, x+1, y+1) && board[x+1][y+1] == 'M') m++;

            if (!out(board, x+1, y) && board[x+1][y] == 'M') m++;

            if (m) {

                board[x][y] = '0'+m;

            } else {

                board[x][y] = 'B';

                reveal(board, x-1, y-1);

                reveal(board, x-1, y);

                reveal(board, x-1, y+1);

                reveal(board, x, y-1);

                reveal(board, x, y+1);

                reveal(board, x+1, y-1);

                reveal(board, x+1, y+1);

                reveal(board, x+1, y);

            }

        }

    }

};

巴特西

LN : leetcode 529 Minesweeper

lc 529 Minesweeper

递归 Accepted##

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