PPK(outdated)
compute recursively a new string made of only of the parenthesis
and their contents parenBit("x(hello)") → "(hello)"
if(str.startsWith("(") && str.endsWith(")")) return str;
return parenBit(str.substring(str.indexOf('('), str.indexOf(')')+1));
13. Given a string, return recursively a "cleaned" string where
adjacent chars that are the same have been reduced to a single char.
stringClean("yyzzza") → "yza"
if(str.length()<2) return str;
if(str.charAt(1)==str.charAt(0)) return stringClean(str.substring(1));
return str.charAt(0) + stringClean(str.substring(1));
14. Given a string and a non-empty substring sub, compute
recursively the largest substring which starts and ends with sub and
return its length. strDist("catcowcat", "cat") → 9
return func(str, sub).length(); }
private String func(String str, String sub) {
annaabi.ee 
