Minesweeper

Minesweeper.java

class Solution {
    
    int width;
    int height;
    
    Queue<Point> q;
    HashSet<Integer> h;
    
    class Point {
        int x;
        int y;
        
        Point(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }
    
    private void addQueue(char[][] board, int x, int y) {
        if (x < 0 || x == width || y < 0 || y == height) {
            return;
        }
        
        if (board[x][y] != 'E') {
            return;
        }
 
        if (!h.contains(x * 100 + y)) {
            h.add(x * 100 + y);
            q.add(new Point(x, y));
        }
    }
    
    
    public char[][] updateBoard(char[][] board, int[] click) {
        int x = click[0];
        int y = click[1];
        
        if (board[x][y] == 'M') {
            board[x][y] = 'X';
            return board;
        }
        
        if (board[x][y] != 'E') {
            return board;
        }
        
        width = board.length;
        height = board[0].length;
  
        List<Point> mines = new ArrayList<Point>();
        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                if (board[i][j] == 'M') {
                    mines.add(new Point(i, j));
                }
            }
        }
        
        h = new HashSet<Integer>();
        h.add(x * 100 + y);
        
        q = new ArrayDeque<Point>();
        q.add(new Point(x, y));
        
        while (q.peek() != null) {
            Point p = q.poll();
            int adjacentMines = 0;
            for (Point m : mines) {
                if (Math.abs(m.x - p.x) < 2 && Math.abs(m.y - p.y) < 2) {
                    adjacentMines++;
                }
            }
            
            if (adjacentMines == 0) {
                board[p.x][p.y] = 'B';
                
                addQueue(board, p.x-1, p.y-1);
                addQueue(board, p.x-1, p.y);
                addQueue(board, p.x-1, p.y+1);
                addQueue(board, p.x, p.y-1);
                addQueue(board, p.x, p.y+1);
                addQueue(board, p.x+1, p.y-1);
                addQueue(board, p.x+1, p.y);
                addQueue(board, p.x+1, p.y+1);
            } else {
                board[p.x][p.y] = (char) (adjacentMines + 48);   
            }
        }
        
        return board;
    }
}