Solution: Count and Say
Explore how to solve the count and say sequence problem by applying run-length encoding and the knowing what to track pattern. This lesson guides you through building each term by grouping consecutive digits, helping you write an efficient algorithm for generating the n-th sequence string.
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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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