Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

sameFirstLast

Posted on 2015-02-12
8
Medium Priority
?
68 Views
Last Modified: 2015-02-18
hi,
I am trying below challenge
http://codingbat.com/prob/p118976

i am failing in one test case
public boolean sameFirstLast(int[] nums) {
int numsLen=nums.length;
int first=nums[0];
int last=nums[numsLen-1];
if(numsLen>=1&&first==last)
return true;
return false;
  
}

Open in new window


Expected	Run		
sameFirstLast({1, 2, 3}) → false	false	OK	    
sameFirstLast({1, 2, 3, 1}) → true	true	OK	    
sameFirstLast({1, 2, 1}) → true	true	OK	    
sameFirstLast({7}) → true	true	OK	    
sameFirstLast({}) → false	Exception:java.lang.ArrayIndexOutOfBoundsException: 0 (line number:3)	X	    
sameFirstLast({1, 2, 3, 4, 5, 1}) → true	true	OK	    
sameFirstLast({1, 2, 3, 4, 5, 13}) → false	false	OK	    
sameFirstLast({13, 2, 3, 4, 5, 13}) → true	true	OK	    
sameFirstLast({7, 7}) → true	true	OK	    
other tests

Open in new window


please advise
0
Comment
Question by:gudii9
  • 2
  • 2
  • 2
  • +1
8 Comments
 
LVL 7

Author Comment

by:gudii9
ID: 40606504
public boolean sameFirstLast(int[] nums) {

int numsLen=nums.length;

if(numsLen==0){

return false;
}
int first=nums[0];
int last=nums[numsLen-1];
if(numsLen>=1&&first==last)
return true;
return false;
  
}

Open in new window

i think i oredere edge case and passed all tests. I wonder how to improve my code. please advise
0
 
LVL 28

Assisted Solution

by:dpearson
dpearson earned 668 total points
ID: 40606507
I would say your code actually looks fine.

The only part that could be written more clearly is to replace these 3 lines:

...
if(numsLen>=1&&first==last)
return true;
return false;
...

With this one line:

return (first == last) ;

There's no need to check that "numsLen >= 1" because you already tested for length 0 at the top of the method - so the length here must be >= 1.

And rather than:
   if (first == last)
       return true ;
  return false ;

you can just return whether "first == last"
   return (first == last) ;

Make sense?

Whole program becomes:

public boolean sameFirstLast(int[] nums) {

int numsLen=nums.length;

if(numsLen==0){

return false;
}
int first=nums[0];
int last=nums[numsLen-1];
return (first == last) ;
}

Open in new window

0
 
LVL 85

Expert Comment

by:ozo
ID: 40606510
numsLen>=1&& is unneccessary
and at that point, you can just
return first==last;

or, using numsLen>=1&&  you can make the if(numsLen==0){ unnecessary
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 7

Author Comment

by:gudii9
ID: 40606523
And rather than:
   if (first == last)
       return true ;
  return false ;

you can just return whether "first == last"
   return (first == last) ;

Open in new window


instead of doing in 2 steps like checking and then returning we are doing in one step in return itself comparing so that i will automatically give true false in return statement right?
please advise
0
 
LVL 85

Assisted Solution

by:ozo
ozo earned 664 total points
ID: 40606542
first == last is true when the operands are equal, and false when they are not equal
0
 
LVL 28

Expert Comment

by:dpearson
ID: 40606710
instead of doing in 2 steps like checking and then returning we are doing in one step in return itself comparing so that i will automatically give true false in return statement right?

Yes that's right.  We're replacing 3 lines of code with 1 - which is good because it's simpler.  And we're also removing a conditional (the "if" test) so the code always executes the same lines of code - which is also good.

Rather than:
   if (first == last) {
      // Sometimes we run code in here
      return true ;
   }
   // Sometimes we run code here
   return false ;

We have now:
   // Always run this code
   return (first == last) ;

It's best to avoid branches and conditional statements in your code where possible.  It makes bugs less likely.

Doug
0
 
LVL 37

Accepted Solution

by:
zzynx earned 668 total points
ID: 40614484
If you write:
 if (first == last) {
       return true ;
 }
 return false ;

Open in new window


When runing this piece of code, your computer will evaluate the expression first == last.
The value of an expression is a boolean. That's a variable that can hold the value 'true' or 'false'.
When the result/value of that expression is true, it will return true.
When the result/value of that expression is false, it will return false.
So, in fact, it can just return the result/value of that expression.
You write that as:
return first == last;

Open in new window

0
 
LVL 37

Expert Comment

by:zzynx
ID: 40616024
Thanx 4 axxepting
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

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.

Question has a verified solution.

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

In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Article by: evilrix
Looking for a way to avoid searching through large data sets for data that doesn't exist? A Bloom Filter might be what you need. This data structure is a probabilistic filter that allows you to avoid unnecessary searches when you know the data defin…
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.
Suggested Courses

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

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

Join & Ask a Question