I knew the pattern conceptually but fumbled the loop logic on the first pass.
Start by clarifying the problem and edge cases, then explain the iterative approach: generate each term from the previous by scanning and counting consecutive identical digits. Emphasize that the sequence is built iteratively, and discuss time and space complexity.
Pro tip: Mention that the sequence grows exponentially in length, so for large n, memory and time become significant; you can optimize by using a StringBuilder or list of characters to avoid repeated string concatenation.
Confirm the definition of the sequence, starting term (usually '1' for n=1), and constraints (e.g., n >= 1). Ask about input size to discuss performance implications.
Explain that you will start with the first term and iteratively generate the next term by scanning the current term, counting consecutive identical digits, and appending the count followed by the digit.
Demonstrate with a small n, e.g., n=4: 1 -> 11 -> 21 -> 1211, to show how the run-length encoding works.
Describe using a loop for n-1 iterations, and within each iteration, a two-pointer or single-pass scan to build the next term. Mention using a StringBuilder for efficiency.
State that time complexity is O(total length of all terms up to n), which grows exponentially, and space complexity is O(length of the nth term). Handle edge cases like n=1.
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