Get Optimal String Length

Problem Overview

• Find the maximum length of a string built from 'A' and 'B' under run-length and total count limits.
• Input: countA, countB, maxA, maxB; Output: long integer length; Constraints: 0 ≤ all ≤ 1e6.
• Each run of 'A' ≤ maxA and each run of 'B' ≤ maxB; total 'A's ≤ countA and 'B's ≤ countB.
• Real-world context: HackerRank trivia scenario; classic string construction problem for coding interview prep.
• Source: Ibm interviews; a practical interview question often seen in problem sets.