Java > Recursion-1 > strDist (CodingBat Solution)

Problem:

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
strDist("catcowcat", "cow") → 3
strDist("cccatcowcatxx", "cat") → 9


Solution:

public int strDist(String str, String sub) {
  return func(str, sub).length();  
}

private String func(String str, String sub) {
  int strlen = str.length();
  int sublen = sub.length();
  if (str.equals("")) return str;
  if (str.startsWith(sub)) {
    if (str.substring(strlen-sublen, strlen).equals(sub))
      return str;
    else
      return func(str.substring(0, strlen-1), sub);
  }
  else
    return func(str.substring(1), sub);
}

13 comments:

  1. UnknownSeptember 7, 2015 at 4:48 AM

    public int strDist(String str, String sub) {
    if(str.length()==sub.length()&&str.equals(sub))return str.length();
    else if(str.length()<=sub.length())return 0;
    else if(str.substring(0,sub.length()).equals(sub)){
    if(str.length()>sub.length()&&str.substring((str.length()-sub.length()),str.length()).equals(sub))
    return str.length();
    else
    return strDist(str.substring(0,str.length()-1),sub);
    }
    return strDist(str.substring(1),sub);
    }

    ReplyDelete
  2. AnonymousOctober 15, 2015 at 11:04 PM

    public int strDist(String str, String sub) {
    if (!str.equals(sub) && str.length() <= sub.length()) return 0;
    if (!str.startsWith(sub)) return strDist(str.substring(1, str.length()), sub);
    if (!str.endsWith(sub)) return strDist (str.substring(0, str.length()-1), sub);
    return str.length();

    }

    ReplyDelete
    Replies
    1. AnonymousJune 27, 2016 at 7:19 PM

      public int strDist(String str, String sub) {
      if (str.length() < sub.length()) return 0;
      if (!str.startsWith(sub)) return strDist(str.substring(1, str.length()), sub);
      if (!str.endsWith(sub)) return strDist (str.substring(0, str.length()-1), sub);
      return str.length();
      }

      Delete
  3. UnknownNovember 6, 2015 at 9:52 AM

    public int strDist(String str, String sub) {

    if (str.startsWith(sub) && str.endsWith(sub)){
    return str.length();
    }
    else if (!str.startsWith(sub)){
    if (str.length() > 1)
    return strDist(str.substring(1), sub);
    else
    return 0;
    }
    else if (!str.endsWith(sub)){
    if (str.length() > 0)
    return strDist(str.substring(0, str.length()-1), sub);
    else
    return 0;
    }
    else{
    return 0;
    }
    }

    ReplyDelete
  4. AnonymousMay 12, 2017 at 10:14 PM

    public int strDist(String str, String sub) {
    if(str.equals(sub))
    return sub.length();
    else if(str.length() < sub.length())
    return 0;
    else if(str.substring(0,sub.length()).equals(sub))
    {
    if(str.substring(str.length() - sub.length()).equals(sub))
    return str.length();
    else return strDist(str.substring(0,(str.length() -1)),sub);
    }
    else return strDist(str.substring(1), sub);
    }

    ReplyDelete
  5. UnknownJanuary 17, 2019 at 3:44 PM

    I didn't do it recursively but it still works!!!!

    public int strDist(String str, String sub) {
    if (!(str.contains(sub))) {
    return 0;
    }
    return str.substring(str.indexOf(sub), str.lastIndexOf(sub)).length() + sub.length();
    }

    ReplyDelete
    Replies
    1. UnknownJuly 3, 2020 at 6:43 AM

      public int strDist(String str, String sub) {
      return str.lastIndexOf(sub) != -1 ? str.lastIndexOf(sub) - str.indexOf(sub) + sub.length() : 0;
      }

      Delete
  6. AnonymousFebruary 24, 2019 at 8:45 PM

    public int strDist(String str, String sub) {
    int len=str.length();
    int sl=sub.length();
    if(str.equals(""))
    return 0;
    if(str.startsWith(sub)){
    if(str.substring(len-sl,len).equals(sub))
    return len;
    else
    return strDist(str.substring(0,len-1),sub);
    }
    else
    return strDist(str.substring(1),sub);
    }

    ReplyDelete
  7. lakohotJuly 28, 2019 at 3:49 AM

    public int strDist(String str, String sub) {
    if (!(str.contains(sub))) return 0;
    if (!(str.startsWith(sub))) return strDist(str.substring(1), sub);
    if (!(str.endsWith(sub))) return strDist(str.substring(0, str.length() - 1), sub);
    return str.length();
    }

    ReplyDelete
  8. UnknownJuly 3, 2020 at 8:42 AM

    public int strDist(String str, String sub) {

    if (str.length()2){
    return strDist(str.substring(1,str.length()-1), sub);
    }

    return 0;
    }

    ReplyDelete
  9. UnknownJuly 19, 2020 at 1:59 PM

    public int strDist(String str, String sub) {
    if (str.length() < sub.length())
    {
    return 0;
    }
    if (str.substring(0, sub.length()).equals(sub) && str.substring(str.length() - sub.length()).equals(sub))
    {
    return str.length();
    }
    else
    {
    if (!str.substring(0, sub.length()).equals(sub))
    {
    return strDist(str.substring(1), sub);
    }
    else
    {
    return strDist(str.substring(0, str.length() - 1), sub);
    }
    }
    }

    ReplyDelete
  10. AnonymousSeptember 16, 2020 at 6:29 AM

    public int strDist(String str, String sub) {
    if(str.length() < sub.length()
    || str.indexOf(sub) == -1){
    return 0;
    }
    if(!str.substring(0, sub.length()).equals(sub)){
    return strDist(str.substring(str.indexOf(sub)), sub);
    }
    if(!str.substring(str.length() - sub.length()).equals(sub)){
    return strDist(str.substring(0, str.length() - 1), sub);
    }
    return str.length();
    }

    ReplyDelete
  11. jagadeepNovember 24, 2023 at 7:46 AM

    public int strDist(String str, String sub) {
    if (str.length() < sub.length() || str.equals("")) return 0;
    if (str.substring(0, sub.length()).equals(sub)) {
    if (str.substring(str.length()-sub.length(), str.length()).equals(sub)) return str.length();
    else return strDist(str.substring(0, str.length()-1), sub);
    }
    return strDist(str.substring(1), sub);
    }

    ReplyDelete