38 - Count and Say

 JAVA

• class Solution {
      public String countAndSay(int n) {
          String s = "1";
          while (--n > 0) {
              StringBuilder t = new StringBuilder();
              for (int i = 0; i < s.length();) {
                  int j = i;
                  while (j < s.length() && s.charAt(j) == s.charAt(i)) {
                      ++j;
                  }
                  t.append((j - i) + "");
                  t.append(s.charAt(i));
                  i = j;
              }
              s = t.toString();
          }
          return s;
      }
  }

C++

• class Solution {
  public:
      string countAndSay(int n) {
          string s = "1";
          while (--n) {
              string t = "";
              for (int i = 0; i < s.size();) {
                  int j = i;
                  while (j < s.size() && s[j] == s[i]) ++j;
                  t += to_string(j - i);
                  t += s[i];
                  i = j;
              }
              s = t;
          }
          return s;
      }
  };