code: public String getLCS(String strA, String strB) {
          if ("".equals(strA)) {
              return "";
          }
  
          StringBuilder sb = new StringBuilder();
          algC(sb, strA.length(), strB.length(), strA, strB);
          return sb.toString();
      }
docs: Gets the Longest Common Subsequence of two strings, using Dynamic
  programming techniques, and minimal memory
  
  @param strA the first String
  @param strB the second String
  @return the Longest Common Subsequence of strA and strB