You are given an unknown rectangular room represented as a grid. Each cell is either:

• An empty cell that the robot can move through.
• A blocked cell that the robot cannot enter.

A robot starts from an unknown empty cell, initially facing one of the four cardinal directions (up, right, down, or left). The layout of the room is not available to your program. Instead, you can interact with the robot only through the following operations:

• Move forward by one cell.
• Rotate left by 90°.
• Rotate right by 90°.
• Clean the current cell.

If the robot attempts to move into a blocked cell, it remains in its current position.

Your task is to clean every reachable empty cell exactly once or more using only these operations.

Implement the required algorithm to ensure that all reachable cells are cleaned.

Robot Interface

The following operations are available:

bool move();      // Moves forward if possible.
                  // Returns true if the move succeeds, otherwise false.

void turnLeft();  // Rotates the robot 90° to the left.

void turnRight(); // Rotates the robot 90° to the right.

void clean();     // Cleans the current cell.

Function Signature

void cleanRoom(Robot& robot);

Constraints

• The room dimensions are at most 100 × 200.
• The starting cell is guaranteed to be empty.
• The room layout is unknown to your algorithm.
• All robot operations run in constant time.

Notes

• You must not assume access to the room grid or the robot's coordinates.
• The robot's initial position and initial facing direction are unknown.
• The solution should visit every reachable empty cell and invoke clean() on each of them.