Implement multiple coding round problems

Solve the following coding problems.

1) Bus schedule (next departure)

Given:

• A sorted list buses[] of bus departure times (minutes since 00:00).
• A list arrivals[] of passenger arrival times (minutes since 00:00).

For each passenger, return the earliest bus departure time that is >= their arrival time, or -1 if no such bus exists.

Constraints:

• 1 <= len(buses), len(arrivals) <= 2e5
• Times fit in 32-bit signed integers.

2) Priority boarding order

You are given a list of passengers. Each passenger has:

• priority (smaller number = higher priority, e.g. 0 is best)
• checkInTime (integer)
• name (string)

Output the boarding order under these rules:

1. Higher priority boards first.
2. Within the same priority, earlier checkInTime boards first.
3. If still tied, preserve input order.

Follow-up: If passengers arrive as a stream, how would you produce the next passenger to board efficiently?

3) Decode passwords from a stream with limited reads

A file/stream contains multiple passwords encoded as (index, char) pairs in order of appearance. A password is defined by indices 0..L-1 appearing exactly once each, where L is the password length.

Rules:

• The first password is guaranteed valid .
• When parsing the stream, encountering an index that has already appeared in the current password indicates the start of the next password (i.e., the pair you just read belongs to the next password).
• You cannot load the full file into memory. You may only read in chunks whose size is at most the length L of the first decoded password .

Return all decoded passwords in order.

4) Evaluate an arithmetic expression with up to two variables

Given:

• A string expression expr containing integers, + and - , parentheses ( ) , optional whitespace, and variable names consisting of letters.
• The expression contains at most two distinct variable names .
• A map of variable values (e.g., {x: 3, y: 10} ), guaranteed to include any variables present.

Compute and return the integer result.

Note: You may not assume there are spaces between tokens.