Count N Say

Solution.cs

using System.Text;

public class Solution {
  public string CountAndSay(int n) {
    if(n == 1) return "1";
    
    var previousSay = CountAndSay(n - 1);
    StringBuilder sb = new StringBuilder();
    
    int runningOcc = 1;
    char runningChar = previousSay[0];
    for(int i = 0; i < previousSay.Length; i++)
    {
      if(i == 0)
      {
        runningOcc = 1;
        runningChar = previousSay[i];
      }
      else if(runningChar == previousSay[i])
      {
        runningOcc++;
      }
      else
      {
        sb.Append(runningOcc).Append(runningChar);
        runningOcc = 1;
        runningChar = previousSay[i];
      }
      
      if(i == previousSay.Length - 1)
      {
        sb.Append(runningOcc).Append(runningChar);
      }
    }
    
    return sb.ToString();
  }
}