Solution: Count and Say
Understand how to generate the count and say sequence by efficiently tracking current digits and their counts. This lesson teaches how to apply run-length encoding iteratively to build each term, preparing you to solve similar string manipulation problems with optimal time and space complexity.
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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 stringcountAndSay(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
Constraints:
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