count

Count and Say (Easy 38)

The count-and-say sequence is the sequence of integers with the first five terms as following:

1. 1
   

2. 11
   

3. 21
   

4. 1211
   

5. 111221
   

1 is read off as "one 1" or 11. 11 is read off as "two 1s" or 21. 21 is read off as "one 2, then one 1" or 1211.

Given an integer n where 1 ≤ n ≤ 30, generate the nth term of the count-and-say sequence.

Solution:

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Iterate over string from start. counting group member and group count. Append to result. Iterate n times. O(n * 2n) time, O(n) space.

Installation

Run make to run python and Swift files.