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boolean program

Posted on 2014-10-02
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Last Modified: 2014-10-07
Hi,

I was trying below program challenge
http://codingbat.com/prob/p165701

public boolean loneTeen(int a, int b) {
  if(a>=13&a<=19){
  return true;
  }
  
   if(b>=13&b<=19){
  return true;
  }
  
  return false;
  
}

Open in new window

i wrote as above.

I have four test scenario cases failing

Expected      Run            
loneTeen(13, 99) → true      true      OK         
loneTeen(21, 19) → true      true      OK         
loneTeen(13, 13) → false      true      X         
loneTeen(14, 20) → true      true      OK         
loneTeen(20, 15) → true      true      OK         
loneTeen(16, 17) → false      true      X         
loneTeen(16, 9) → true      true      OK         
loneTeen(16, 18) → false      true      X         
loneTeen(13, 19) → false      true      X         
loneTeen(13, 20) → true      true      OK         
loneTeen(6, 18) → true      true      OK         
loneTeen(99, 13) → true      true      OK         
loneTeen(99, 99) → false      false      OK         
Correct for more than half the tests

Please advise on why they are failing and how to fix it
Please advise
0
Comment
Question by:gudii9
  • 6
  • 4
  • 2
  • +2
15 Comments
 
LVL 26

Accepted Solution

by:
dpearson earned 200 total points
ID: 40358663
Your code is almost correct.

It's just not handling the case where both a and b are teens.  In that case, the instructions say to return false.

Since your code tests to see if a is a teen and if it is, immediately returns true, it gets the case wrong where both a and b are teens.

You may want to consider something like this instead?

public boolean loneTeen(int a, int b) {
  boolean aTeen = (a >= 13 && a <= 19) ;
  boolean bTeen = (b >= 13 && b <= 19) ;
  
  if(aTeen && !bTeen){
  return true;
  }
  
  if(!aTeen && bTeen){
  return true;
  }
  
  return false;

}

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0
 
LVL 37

Assisted Solution

by:zzynx
zzynx earned 100 total points
ID: 40358815
Or in short:

public boolean loneTeen(int a, int b) {
    return (isTeen(a) && !isTeen(b)) || (isTeen(b) && !isTeen(a));
}

private boolean isTeen(int value) {
    return value >= 13 && value <=19;
}

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0
 
LVL 84

Expert Comment

by:ozo
ID: 40358911
//or
return isTeen(a) ^ isTeen(b);
0
 
LVL 37

Expert Comment

by:zzynx
ID: 40358922
Right you are :-)
0
 
LVL 7

Author Comment

by:gudii9
ID: 40361532
I wonder is there is a way i can modify and make my program to work without introducing aTeen and bTeen.
Why we need extra valraibles called aTeen and bTeen in this case.

if(13<=b<=19){
  return true;
 
  }



If i give both conditions together as above i am getting error below. Why i am getting below error. what it means. I thought it should work fine. Please advise

Error:      if(13<=b<=19){
         ^^^^^^^^^
The operator <= is undefined for the argument type(s) boolean, int


see Example Code to help with compile problems
0
 
LVL 7

Author Comment

by:gudii9
ID: 40361540
I tried like below but lot of test cases are failing
public boolean loneTeen(int a, int b) {
  if(13<=a & a <=19){
  return true;
  
  }
  
    if(13<=b & b<=19){
  return true;
  
  }
  
  
  if((13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  if(!(13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  return false;
}

Open in new window


Expected      Run            
loneTeen(13, 99) → true      true      OK         
loneTeen(21, 19) → true      true      OK         
loneTeen(13, 13) → false      true      X         
loneTeen(14, 20) → true      true      OK         
loneTeen(20, 15) → true      true      OK         
loneTeen(16, 17) → false      true      X         
loneTeen(16, 9) → true      true      OK         
loneTeen(16, 18) → false      true      X         
loneTeen(13, 19) → false      true      X         
loneTeen(13, 20) → true      true      OK         
loneTeen(6, 18) → true      true      OK         
loneTeen(99, 13) → true      true      OK         
loneTeen(99, 99) → false      false      OK         


Please advise
0
 
LVL 7

Author Comment

by:gudii9
ID: 40361546
public boolean loneTeen(int a, int b) {
  if(13<=a & a <=19){
  return true;
  
  }
  
    if(13<=b & b<=19){
  return true;
  
  }
  
  
  if((13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  if(!(13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  return false;
}

Open in new window


I wrote as above base on comment ID: 40358663
How is above program differenmt from program in comment ID: 40358663

public boolean loneTeen(int a, int b) {
  if(13<=a & a <=19){
  return true;
  
  }
  
    if(13<=b & b<=19){
  return true;
  
  }
  
  
  if((13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  if(!(13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  return true;
}

Open in new window


If i change the last method return staement from false to true more than half test cases are failing. I wonder why. I though i covered all the 3 major challenge issues in 3 if loops. So i thought method return type either true or false does not matter. But my results prove that i am wrong in my assumption. Please advise

Expected      Run            
loneTeen(13, 99) → true      true      OK         
loneTeen(21, 19) → true      true      OK         
loneTeen(13, 13) → false      true      X         
loneTeen(14, 20) → true      true      OK         
loneTeen(20, 15) → true      true      OK         
loneTeen(16, 17) → false      true      X         
loneTeen(16, 9) → true      true      OK         
loneTeen(16, 18) → false      true      X         
loneTeen(13, 19) → false      true      X         
loneTeen(13, 20) → true      true      OK         
loneTeen(6, 18) → true      true      OK         
loneTeen(99, 13) → true      true      OK         
loneTeen(99, 99) → false      false      OK
0
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LVL 84

Expert Comment

by:ozo
ID: 40361602
loneTeen(13, 13) → false      true      X  
in this case, you should be returning false, but this code immediately returns true
 if(13<=a & a <=19){
  return true;
0
 
LVL 7

Author Comment

by:gudii9
ID: 40362472
public boolean loneTeen(int a, int b) {
  if(13<=a & a <=19){
  return true;
  
  }
  
    if(13<=b & b<=19){
  return true;
  
  }
  
  
  if((13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  if(!(13<=a & a <=19)&!(13<=b & b<=19)){
  return false;
  }
  
  return false;
}

Open in new window


How do i fix above code so that it returns false when both a and b are teens. I do not want to introduce aTeen and bTeen if possible. Please advise
0
 
LVL 7

Author Comment

by:gudii9
ID: 40362477
public boolean loneTeen(int a, int b) {
if((13<=a & a <=19)&!(13<=b & b<=19)){
  return true;
  }
  
  
if(!(13<=a & a <=19)&(13<=b & b<=19)){
  return true;
  }
  
  return false;
}

Open in new window


I wrote as above and passed all the test cases


Expected      Run            
loneTeen(13, 99) → true      true      OK         
loneTeen(21, 19) → true      true      OK         
loneTeen(13, 13) → false      false      OK         
loneTeen(14, 20) → true      true      OK         
loneTeen(20, 15) → true      true      OK         
loneTeen(16, 17) → false      false      OK         
loneTeen(16, 9) → true      true      OK         
loneTeen(16, 18) → false      false      OK         
loneTeen(13, 19) → false      false      OK         
loneTeen(13, 20) → true      true      OK         
loneTeen(6, 18) → true      true      OK         
loneTeen(99, 13) → true      true      OK         
loneTeen(99, 99) → false      false      OK         


Does it look fine?
Please advise
0
 
LVL 26

Expert Comment

by:dpearson
ID: 40362578
Yes this is fine.  You should be using "&&" instead of just "&" but that's all.

Can you see how this code is the same as this code (using the variables) except you've written out the test (a >= 13 && a <= 19) each place where the variable would go?

public boolean loneTeen(int a, int b) {
  boolean aTeen = (a >= 13 && a <= 19) ;
  boolean bTeen = (b >= 13 && b <= 19) ;
 
  if(aTeen && !bTeen){
  return true;
  }
 
  if(!aTeen && bTeen){
  return true;
  }
 
  return false;
}

So yes, what you wrote is fine.

Doug
0
 
LVL 84

Assisted Solution

by:ozo
ozo earned 200 total points
ID: 40362581
If the goal is to pass the test cases, then it is looks fine for that.
0
 
LVL 7

Author Comment

by:gudii9
ID: 40362827
Can you see how this code is the same as this code (using the variables) except you've written out the test (a >= 13 && a <= 19) each place where the variable would go?


yes i see it
0
 
LVL 31

Expert Comment

by:awking00
ID: 40366835
>>Why we need extra valraibles<<
Sometimes they can simplify coding and make it easier to understand. The following passes the test only using three lines of code employing two variables:
public static boolean loneTeen(int a, int b) {
      boolean aVal = a >= 13 && a <= 19;
      boolean bVal = b >= 13 && b <= 19;

      return aVal && !bVal || !aVal && bVal ? true : false;
      }
0
 
LVL 84

Expert Comment

by:ozo
ID: 40366873
//or,
  return (a >= 13 && a <= 19) ^ (b >= 13 && b <= 19);

//or,
  return (a >= 13 && a <= 19) != (b >= 13 && b <= 19);

//or,
  return a >= 13 ^ a <= 19 ^ b >= 13 ^ b <= 19;

//or,
  return a < 13 ^ b < 13 ^ a > 19 ^ b > 19;

//or even
  return (a-13 ^ b-13 ^ 19-a ^ 19-b)<0;
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