Solution: Count and Say
Understand how to generate the count and say sequence by iteratively describing the previous term using run-length encoding. This lesson teaches you to track consecutive digits effectively, enabling you to build each next string with a single pass. You will develop skills to handle sequences in coding interviews by applying the knowing what to track pattern.
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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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