java 网格照明（Dropbox Q）

Posted 2021-05-08

public class Lamps{
	private boolean[] columns, rows, diagonalsLeft, diagonalsRight;

	public Lamps(int size, int[][] lamps){
		this.columns = new boolean[size];
		this.rows = new boolean[size];
		this.diagonalsLeft = new int[(size) * 2 - 2];  or (size - 1) * 2 + 1
		this.diagonalsRight = new int[(size) * 2 - 2];

		
		for(int[] lampcoor : lamps){
			int row = lampcoor[0];
			int col = lampcoor[1];

      //check if this x,y is out of 8 adjacent cells of queried box.
      if(row > x+1 || row < x-1 || col < y-1 || col > y+1){
           this.columns[row] = true;
			     this.rows[col] = true;
			     this.diagonalsLeft[row + col] = true;
			     this.diagonalsRight[row - col] = true;  // take abs difference
		   }
		}
	}

	public boolean query(int x, int y){
		if(columns[x] || rows[y] || diagonalsLeft[x + y] || this.diagonalsRight[x - y])
			return true;
	}


}