Problem Description

Given an array prices where prices[i] represents the stock price on day i, you are required to solve two related tasks under specific "forced-trade" constraints.

Task A: Exactly One Transaction

Choose exactly one buy day and one later sell day to maximize profit. If prices never rise, you must still perform a transaction and return the least possible loss.

Task B: Exactly Two Transactions

Choose exactly two non-overlapping buy-sell pairs (meaning the first transaction's sell day must occur before the second transaction's buy day) to maximize total profit. If necessary, you must include losses to ensure exactly two transactions are performed.

Implementation Requirements

Implement two distinct functions, for example, profitExactlyOne(prices) and profitExactlyTwo(prices), to address Task A and Task B respectively.

Assumptions and Constraints

• Each transaction involves a single share.
• There are no transaction costs.
• Short selling is not permitted (i.e., you must buy before you sell).
• Handle edge cases gracefully, such as empty or single-element prices arrays.
• No explicit time-complexity requirement is given, but efficient solutions are expected.