public boolean isLegalVale(int number) {
			int squareIndex = (r / PART) * PART  + c / PART;
			if (squares.get(squareIndex).contains(new Integer(number)))
				return false;
			for (int x = 0; x < SIZE; x++) {
				if (grid[r][x] == number || grid[x][c] == number)
					return false;
			}
			return true;
		}