Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
Solved

# countHi2 challenge

Posted on 2016-09-23
Medium Priority
82 Views
Hi,

I am working on below challenge.
http://codingbat.com/prob/p143900
Psedo code:
1. check the given string starts with hi and does not have x infront of it
2.if true increment by 1 and call recursive function
3. if false call recusive function again

I wrote my code as below and not passing all tests
``````public int countHi2(String str) {
if (str.length() <2){
return 0;
}
if (str.startsWith( "hi")&!str.startsWith("xhi")) {
return 1 + countHi2(str.substring(2));
}
else {
return countHi2(str.substring(1));

}

}
``````

Expected      Run
countHi2("ahixhi") → 1      2      X
countHi2("ahibhi") → 2      2      OK
countHi2("xhixhi") → 0      2      X
countHi2("hixhi") → 1      2      X
countHi2("hixhhi") → 2      2      OK
countHi2("hihihi") → 3      3      OK
countHi2("hihihix") → 3      3      OK
countHi2("xhihihix") → 2      3      X
countHi2("xxhi") → 0      1      X
countHi2("hixxhi") → 1      2      X
countHi2("hi") → 1      1      OK
countHi2("xxxx") → 0      0      OK
countHi2("h") → 0      0      OK
countHi2("x") → 0      0      OK
countHi2("") → 0      0      OK
countHi2("Hellohi") → 1      1      OK
other tests
X
Any improvements or alternate approaches?

0
Question by:gudii9
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• Learn & ask questions
• 4
• 3

LVL 28

Expert Comment

ID: 41812810
Your error in logic is this line
``````if (str.startsWith( "hi")&!str.startsWith("xhi"))
``````
You will have to break this up into two conditionals. If str starts with "xhi" then skip 3 indexes.
0

LVL 7

Author Comment

ID: 41813030
``````public int countHi2(String str) {
if (str.length() <2){
return 0;
}
if (str.startsWith( "hi")) {
if(!str.startsWith("xhi")){
return 1 + countHi2(str.substring(2));
}
}
else {
return countHi2(str.substring(1));

}

}
``````

something like above
I keep getting below error many times
Compile problems:

Error:      public int countHi2(String str) {
^^^^^^^^^^^^^^^^^^^^
This method must return a result of type int

Possible problem: the if-statement structure may theoretically
allow a run to reach the end of the method without calling return.
Consider adding a last line in the method return some_value;
so a value is always returned.

0

LVL 28

Expert Comment

ID: 41813249
I will try to write pseudo code for  the code you posted.

if(length of str is less than 2) return 0
if(str starts with hi and does not starts with xhi)
return 1 + whatever countHi2(str minus the first two characters) returns
else return whatever countHi2(str minus the first character) returns

In the second if statement, you and I know that that if str starts with hi then it can't start with xhi(mutually exclusive). But the compiler doesn't know that. So, the compiler thinks that the first condition(start with hi) could be true and the second condition(start with xhi) could be false. If that did happen, then your code wouldn't return anything.  That is why you get that error.
Anyway, as I posted above here, you will have to break this up into two separate conditionals. If str starts with "xhi" then skip 3 indexes.
0

LVL 7

Author Comment

ID: 41813335
``````public int countHi2(String str) {
if (str.length() <2){
return 0;
}
if (str.startsWith( "hi")) {

return 1 + countHi2(str.substring(2));
}

if (str.startsWith( "xhi")) {

return countHi2(str.substring(3));
}

else {
return countHi2(str.substring(1));
}
}
/*if(length of str is less than 2) return 0
if(str starts with hi and does not starts with xhi)
return 1 + whatever countHi2(str minus the first two characters) returns
else return whatever countHi2(str minus the first character) returns */
``````

above passes all tests. any improvement or alternate approaches?
0

LVL 28

Accepted Solution

rrz earned 2000 total points
ID: 41813356
My code is the same as yours. Personally, I like to format it differently.
``````public int countHi2(String str) {
if(str.length() < 2)return 0;
if(str.startsWith("xhi"))return countHi2(str.substring(3));
if(str.startsWith("hi"))return 1 + countHi2(str.substring(2));
return countHi2(str.substring(1));
}
``````
0

LVL 7

Author Comment

ID: 41813358
``````if(str.startsWith("xhi"))return countHi2(str.substring(3));
if(str.startsWith("hi"))return 1 + countHi2(str.substring(2));
``````
your order as above is reverse compared to my order as below

`````` if (str.startsWith( "hi")) {

return 1 + countHi2(str.substring(2));
}

if (str.startsWith( "xhi")) {

return countHi2(str.substring(3));
}

``````

does it matter the order here or in general??
0

LVL 28

Expert Comment

ID: 41813372
does it matter the order here or in general??
In general, it probably matters. But, in this case it doesn't matter.
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
Java functions are among the best things for programmers to work with as Java sites can be very easy to read and prepare. Java especially simplifies many processes in the coding industry as it helps integrate many forms of technology and different d…
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.
This video teaches viewers about errors in exception handling.
###### Suggested Courses
Course of the Month4 days, 21 hours left to enroll

#### 670 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.