38. Count and Say

The count-and-say sequence is a sequence of digit strings defined by the recursive formula:

• countAndSay(1) = "1"

• countAndSay(n) is the way you would "say" the digit string from countAndSay(n-1), which is then converted into a different digit string.

To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.

For example, the saying and conversion for digit string "3322251":

Given a positive integer n, return the nth term of the count-and-say sequence.

Example 1:

Input: n = 1
Output: "1"
Explanation: This is the base case.

Example 2:

Input: n = 4
Output: "1211"
Explanation:
countAndSay(1) = "1"
countAndSay(2) = say "1" = one 1 = "11"
countAndSay(3) = say "11" = two 1's = "21"
countAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"

public class Solution {
    public string CountAndSay(int n) {
        
        var base_num = 1;
        var current_array = new int[] {base_num};
        var output = "";
      
        if(n == 1){
          return base_num.ToString();
        }
        
        for(int i = 1; i < n; i++){
          current_array = Calculation(current_array);
        }
        
        output = string.Join("", current_array);
      return output;
        
    }
    
    public int[] Calculation(int[] input_array){
      var new_array = new List<int>();
      var count = 1;
      for(int i = 0; i < input_array.Length; i++){
        if(i + 1 < input_array.Length && input_array[i+1] == input_array[i]){
            count += 1;
        }
        else{
          new_array.Add(count);
          new_array.Add(input_array[i]);
          Console.WriteLine(count);
          count = 1;
        }
      }
      return new_array.ToArray();
    }
}