You are given an array, prices, where prices[i] represents the stock price on day $i$.

Determine the maximum profit you can achieve by making at most two transactions. Each transaction consists of a single buy followed by a single sell.

Note: Each transaction must be completed before starting another, i.e, you must sell the stock before making a new purchase, and only one stock can be held at any time.

Constraints:

• $1 \leq$ prices.length $\leq 10^5$ ...