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modThree challenge

Posted on 2016-08-07
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Last Modified: 2016-08-08
I am working on below challenge

http://codingbat.com/prob/p159979

Psedo code description of approach :
1. Loop throguh given array
2. check if array adjacent three elements are even or odd
3. if yes return true
4. if no return false

I wrote my code as below

public boolean modThree(int[] nums) {
  boolean result=false;
  
  for(int i=0;i<nums.length-2;i++){
    if(nums[i]%2==0&&nums[i+1]%2==0&&nums[i+2]%2==0){
      result=true;
      return result;
    }
    
    else if(nums[i+1]%2==0&&nums[i+2]%2==0&&nums[i+3]%2==0){
      result=true;
      return result;
    }
    
     else if(nums[i]%2==1&&nums[i+1]%2==1&&nums[i+2]%2==1){
      result=true;
      return result;
    }
    
    else if(nums[i+1]%2==1&&nums[i+2]%2==1&&nums[i+3]%2==1){
      result=true;
      return result;
    }
    
    
    else{
      result=false;
    }
    //return result;
  }
  return result;
}

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I am failing couple of  tests
Expected      Run            
modThree([2, 1, 3, 5]) → true      true      OK      
modThree([2, 1, 2, 5]) → false      false      OK      
modThree([2, 4, 2, 5]) → true      true      OK      
modThree([1, 2, 1, 2, 1]) → false      false      OK      
modThree([9, 9, 9]) → true      true      OK      
modThree([1, 2, 1]) → false      false      OK      
modThree([1, 2]) → false      false      OK      
modThree([1]) → false      false      OK      
modThree([]) → false      false      OK      
modThree([9, 7, 2, 9]) → false      false      OK      
modThree([9, 7, 2, 9, 2, 2]) → false      Exception:java.lang.ArrayIndexOutOfBoundsException: 6 (line number:10)      X      
modThree([9, 7, 2, 9, 2, 2, 6]) → true      true      OK
How to improve my design, approach, code? please advise
0
Comment
Question by:gudii9
4 Comments
 
LVL 27

Expert Comment

by:d-glitch
ID: 41746612
There is one else in your pseudo code, but four in you code.
What does that mean?
0
 
LVL 4

Accepted Solution

by:
Hammadh Abdul Rahman earned 250 total points
ID: 41746640
Just remove lines 10-13 and 20-23. Also, the else block is unnecessary.

As the message says, ArrayIndexOutOfBoundsException is occurring at line 10. The same error is possible at line 20 also.

This is because of the reference to nums[i+3]. modThree([9, 7, 2, 9, 2, 2]) would give a array of length 6. Since i<nums.length-2 is the loop condition, max 'i' value would be 3. So nums[3+3] would give error because highest index is 5.
0
 
LVL 31

Assisted Solution

by:awking00
awking00 earned 250 total points
ID: 41747460
Again, I might suggest starting at index = 2 and searching backwards (e.g. if i is even and i-1 and i-2 are even or i is odd and i-1 and i-2 are odd) to avoid any invalid index. Note, you would need to check for a minimum array length of 3.
0
 
LVL 7

Author Comment

by:gudii9
ID: 41747599
public boolean modThree(int[] nums) {
  boolean result=false;
  
  for(int i=0;i<nums.length-2;i++){
    if(nums[i]%2==0&&nums[i+1]%2==0&&nums[i+2]%2==0){
      result=true;
      return result;
    }
    
  
     else if(nums[i]%2==1&&nums[i+1]%2==1&&nums[i+2]%2==1){
      result=true;
      return result;
    }
    //return result;
  }
  return result;
}

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above passed all tests
0

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