38. Count and Say

 1 public String countAndSay(int n) {
 2         if(n == 0) {
 3              return "";
 4          }
 5          if(n == 1) {
 6              return "1";
 7          }
 8          String nth = String.valueOf(11);
 9          for(int i = 0; i < n - 2; i++) {
10              nth = helper(nth);
11          }
12          return nth;
13         
14     }
15     
16     private String helper(String n) {
17         StringBuilder sb = new StringBuilder();
18         StringBuilder resString = new StringBuilder();
19         sb.append(n);
20         int i = 0;
21         while(i < sb.length()) {
22             char x =  sb.charAt(i);
23             i++;
24             int cnt = 1;
25             while(i < sb.length() && sb.charAt(i) == x) {
26                 cnt ++;
27                 i++;
28             }
29             resString.append(cnt);
30             resString.append(x);
31         }
32         return resString.toString();
33     }