Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 139
  • Last Modified:

count11 challenge

Hi,

I am working on below challenge.
http://codingbat.com/prob/p167015
Psedo code:
1. check the array length 0  or 1 then retun 0
2.else if string does not consist of 11  return 0
3.else increment by 1 and calling same recursion function

I wrote my code as below and not passing all tests

public int count11(String str) {
  
  
  
 CharSequence cs1="11";
 
 //CharSequence cs2="aba";
  if(str.length()==0||str.length()==1||str.length()==2){
    return 0;
  }


  else if(!str.contains(cs1)){
    return 0;
  }
  else return 1+count11(str.substring(1));

}

Open in new window


Expected      Run            
count11("11abc11") → 2      5      X      
count11("abc11x11x11") → 3      9      X      
count11("111") → 1      1      OK      
count11("1111") → 2      2      OK      
count11("1") → 0      0      OK      
count11("") → 0      0      OK      
count11("hi") → 0      0      OK      
count11("11x111x1111") → 4      9      X      
count11("1x111") → 1      3      X      
count11("1Hello1") → 0      0      OK      
count11("Hello") → 0      0      OK      
other tests
X      

Any improvements or alternate approaches?      

please advise
0
gudii9
Asked:
gudii9
  • 3
  • 3
1 Solution
 
zzynxSoftware engineerCommented:
This works

public int count11(String str) {
  String string11 = "11";
 
  if(str.length()==0||str.length()==1){
    return 0;
  }

  if(str.startsWith(string11)){
     return 1 + count11(str.substring(2));
  }
  return count11(str.substring(1));
}

Open in new window

0
 
gudii9Author Commented:
how contains different from startsWith method?
why cannot i use contains method here?
public int count11(String str) {
  
  
  
 CharSequence cs1="11";
 
 //CharSequence cs2="aba";
  if(str.length()<3){
    return 0;
  }


  else if(!str.contains(cs1)){
    return 0;
  }
  else return 1+count11(str.substring(2));

}

Open in new window


below also fails?
0
 
gudii9Author Commented:
public int count11(String str) {
  String string11 = "11";
 
  if(str.length()==0||str.length()==1){
    return 0;
  }

  if(str.startsWith(string11)){
     return 1 + count11(str.substring(2));
  }
  return count11(str.substring(1));
}

Open in new window


i like above approach checking if string 11 there then increment by 1 and shift two positions(as duplicats not needed) and call same recursion method
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
zzynxSoftware engineerCommented:
>> i like above approach
OK. Good. :)

Again, you can of course replace
if(str.length()==0||str.length()==1){
    return 0;
}

Open in new window

by
if(str.length()<2){
    return 0;
}

Open in new window


>> why cannot i use contains method
contains() versus startsWith()
The answer is in their names.
0
 
gudii9Author Commented:
>> why cannot i use contains method
contains() versus startsWith()
The answer is in their names.

can you please elaborate.

one to check if starts with a string
other if contains only charactersequence?
0
 
zzynxSoftware engineerCommented:
Starting with a certain string
or
containing a certain string
are two different things.
In this case of recurrence you really need the first one
0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

  • 3
  • 3
Tackle projects and never again get stuck behind a technical roadblock.
Join Now