Solution: Count and Say
Explore the count and say sequence problem where each term describes the previous one through run-length encoding. Learn to efficiently generate the nth term by tracking consecutive digits and their counts in a single pass, optimizing both 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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