Count And Say

Link

Simply iterate through the array counting the number of times a single digit appears and then append it to a stringbuilder.

Full Solution in Java:

 public class Solution {
    public String countAndSay(int n) {
        String s = "1";
        

        
        for(int iter = 1; iter< n; iter++){
            StringBuilder base = new StringBuilder();
            int count = 1;
            for(int i=0; i< s.length()-1; i++){
                if(s.charAt(i)==s.charAt(i+1)){
                    count++;
                }
                else{
                    base.append(count);
                    base.append(s.charAt(i));
                    count = 1;
                }
            }
            base.append(count);
            base.append(s.charAt(s.length()-1));
            s = base.toString();
        }
        
        return s;
 
    }
}