Solve meeting scheduling and robot cleaning tasks

You are given two independent coding problems.

Problem 1: Prioritized Meeting Scheduling

You are asked to schedule meetings in a single meeting room.

You are given an array of meeting requests. Each request is represented as a tuple:

• start : integer start time (inclusive)
• end : integer end time (exclusive), with end > start
• priority : an integer representing the importance / value of that meeting

No two meetings can overlap in time in the single room. Your goal is to choose a subset of non-overlapping meetings to maximize the sum of priorities.

Write a function with the following signature (language-agnostic):

that returns the maximum possible total priority.

Example

Input:

One optimal schedule is to pick meetings (1,3,4) and (3,5,2) for a total priority of 4 + 2 = 6.

Another choice, (0,6,7), has total priority 7, which is better, so the answer is 7.

Constraints

• 1 <= n <= 2 * 10^5 where n is the number of meetings
• 0 <= start < end <= 10^9
• -10^4 <= priority <= 10^4 (priorities can be non‑positive; you may choose to skip such meetings)
• Time complexity should be O(n log n) or better.
• You may assume meetings is given as a list/array in arbitrary order.

Describe the algorithm and then implement the function.

Problem 2: Robot Room Cleaning on an Unknown Grid

You are controlling a vacuum cleaning robot in a 2D grid room. The room is divided into 1x1 cells. Each cell is either empty or blocked. The robot:

• Starts on an empty cell in an unknown position in this room.
• Does not know the layout of the room in advance.
• Only knows about the cell it is currently in and whether the cell in front of it is blocked when it tries to move.

You are given the following interface:

The robot is initially facing up (towards negative y direction in some internal coordinate system you choose).

You must implement a function:

that makes the robot clean all reachable empty cells. You cannot:

• Directly access the room grid or its dimensions.
• Track the robot's absolute position from the environment; you must build your own coordinate system relative to the starting cell.

You can:

• Maintain an internal set of visited coordinates in your own coordinate system (e.g., treat the starting cell as (0,0) ).
• Move, turn, and clean using only the provided API.

Constraints and assumptions

• The number of reachable empty cells is at most 200.
• The room is bounded (finite) but shape and size are unknown.
• The robot must eventually stop after all reachable cells have been cleaned (no infinite loops).

Design an algorithm and implement cleanRoom(Robot robot) to guarantee that all reachable empty cells are cleaned.