Results 1 to 3 of 3
  1. #1
    amexudo is offline Member
    Join Date
    Mar 2008
    Posts
    2
    Rep Power
    0

    Default exercise of recursive method

    hello,
    i was trying to do an exercise but i cannot resolve it.
    the exercise asks us to write a recursive method
    public static int myCompare (String s1, String s2)
    that receives 2 strings and compare them.
    it returns 1 if string s1 comes after s2 in the dictionary (lexicographly)
    the method returns 2 if string s1 comes after s2 in the dictionary
    and it returns 0 if strings s1 and s2 are exactly the same.
    example:
    input:
    s1 = "mother" and s2 = "class"
    output: 1 ('m' comes after 'c')

    the method must be a recursive method and mustn't use loops.

    in the solution it's only allowed to use the following existing methods (from String class):
    public char charAt(int i)
    public String substring(int i)
    public int length()

    thanks for your help!!

  2. #2
    hardwired's Avatar
    hardwired is offline Senior Member
    Join Date
    Jul 2007
    Posts
    1,576
    Rep Power
    9

    Default

    To get you started think about comparing the charAt(0) of each string. If they are the same you remove the first letter from each string and return a call to the method using the substrings as arguments.

  3. #3
    amexudo is offline Member
    Join Date
    Mar 2008
    Posts
    2
    Rep Power
    0

    Default code

    public static int myCompare(String s1, String s2){

    if (s1.charAt(0)==s2.charAt(0)){
    if (s1.length() == 1 && s2.length()!= 1)
    return 2;
    else
    if (s1.length() != 1 && s2.length() ==1)
    return 1;
    else
    if (s1.length()==1 && s2.length() == 1)
    return 0;
    else
    return myCompare(s1.substring(1),s2.substring(1));
    }
    else {
    if (s1.charAt(0)<s2.charAt(0))
    return 2;
    else
    return 1;
    }
    }



    this is what i've done. i think it's right, didn't find any problem till now.
    thanks again for your help!

Similar Threads

  1. Replies: 1
    Last Post: 02-16-2008, 09:10 PM
  2. Replies: 2
    Last Post: 02-16-2008, 08:52 PM
  3. Recursive Method
    By bluegreen7hi in forum New To Java
    Replies: 5
    Last Post: 11-29-2007, 04:45 AM
  4. I/O exercise
    By Feldom in forum New To Java
    Replies: 1
    Last Post: 10-28-2007, 04:48 PM
  5. help with exercise
    By e_as're in forum New To Java
    Replies: 3
    Last Post: 09-25-2007, 10:14 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •