Question

Consider the recursive method whose definition appear below. Why? public static String mysteryString (String s){ if(s.length()==1) return s; else return s.substring(s.length() – 1) + mysteryString(s.substring(0, s.length() – 1)); } What is the result of the following call?
System.out.println(mysteryString("computer"));

Answer 1

Answer:

retupmoc

Explanation:

1.) Anwser will be retupmoc

because

public static String mysteryString(String s){

if(s.length() == 1){

return s;

}

else{

return s.substring(s.length() -1) + mysteryString(s.substring(0, s.length()-1));

}

}

In this program input is "computer" . So the function mysteryString(String s) it does

return s.substring(s.length() -1) + mysteryString(s.substring(0, s.length()-1));

so when it enters the first time ??s.substring(s.length() -1) and it will be give you 'r' then it calls the function recursively by reducing the string length by one . So next time it calls the mysteryString function with string "compute" and next time it calls return s.substring(s.length()-1)? + mysteryString(s.substring(0,s.length-1)) so this time it gives "e" and calls the function again recursively . It keeps on doing till it matched the base case.

so it returns "retupmoc".