145. Fast Buffer Access

In embedded graphics, performance is critical. A generic SPIBus class might safely encapsulate its transmit buffer as private to prevent data corruption by general code. However, the DisplayDriver is a trusted, high-performance module that requires direct access to this buffer to write pixel data rapidly, bypassing the overhead of public setter methods.

Your task is to implement this relationship:

1. Class SPIBus:
   • Has a private array int buffer[2].
   • Has a public method dump() to print the buffer contents.
   • Declares DisplayDriver as a friend class.
2. Class DisplayDriver:
   • Has a method void fastWrite(SPIBus& bus, int v1, int v2).
   • This method directly writes v1 and v2 into bus.buffer[0] and bus.buffer[1].

Program Flow:

1. Instantiate SPIBus and DisplayDriver.
2. Read integer N.
3. Loop N times.
4. Read string cmd.
5. If cmd is "WRITE": Read two integers, call driver.fastWrite.
6. If cmd is "SHOW": Call bus.dump().

Input Format:

• First line: Integer N.
• Next N lines: String cmd ("WRITE", "SHOW"), followed by values.
• Input is provided via standard input (stdin).

Output Format:

• For "SHOW": Buffer: [ <val0> <val1> ]
• Each output on a new line.

Example: Example 1

Input:

3
SHOW
WRITE 55 99
SHOW

Output:

Buffer: [ 0 0 ]
Buffer: [ 55 99 ]

Constraints:

• buffer must be private in SPIBus.
• DisplayDriver must access buffer directly (no public setters in SPIBus).