Solution: Count and Say

Statement

The “count and say” is a sequence of strings built by describing the previous string:

• The sequence starts with countAndSay(1) = “1”

• For n > 1, countAndSay(n) is created by run-length encoding the string countAndSay(n - 1).

Run-length encoding (RLE) works by grouping identical consecutive characters and replacing each group with the count of characters followed by the character itself. For example, the string “15224” is read as: one 1, one 5, two 2s, and one 4, producing “11152214”.

Given a positive integer n, return the $n^{th}$ string in the count-and-say sequence.

Constraints:

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