Problem: Count and Say

Medium

30 min

Explore how to solve the count and say sequence problem by mastering run-length encoding. Understand how to track data efficiently and apply this to permutations, anagrams, and game design. This lesson equips you to implement the sequence and prepares you for related coding interview patterns.

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:

$1 \leq$ n $\leq 30$

Problem: Count and Say

Medium

30 min

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).

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

Constraints:

$1 \leq$ n $\leq 30$

Problem: Count and Say

Statement

Examples

Understand the problem

Figure it out!

Try it yourself

Problem: Count and Say

Statement

Examples

Understand the problem

Figure it out!

Try it yourself