Solved

array220 challenge

Posted on 2016-09-21
8
56 Views
Last Modified: 2016-09-22
Hi,
I am working on below challenge and not cclear on description. please advise

http://codingbat.com/prob/p173469


Recursion-1 > array220
prev  |  next  |  chance
Given an array of ints, compute recursively if the array contains somewhere a value followed in the array by that value times 10. We'll use the convention of considering only the part of the array that begins at the given index. In this way, a recursive call can pass index+1 to move down the array. The initial call will pass in index as 0.

array220([1, 2, 20], 0) → true
array220([3, 30], 0) → true
array220([3], 0) → false
0
Comment
Question by:gudii9
  • 5
  • 3
8 Comments
 
LVL 33

Expert Comment

by:sarabande
ID: 41809324
- recursion stops with false if the index is greater or equal to array length.
- if the index is greater than 0 and nums[index] is equal to 10 times nums[index-1] then stop with success.
- proceed recursion by calling array220 passing the array and the index incremented by 1 and return the result.

Sara
0
 
LVL 7

Author Comment

by:gudii9
ID: 41810760
array220([1, 2, 20], 0) → true
array220([3, 30], 0) → true
array220([3], 0) → false

how above is true and true then false?

array220([1, 2, 20], 0) → true

element at 0 index of above array is 1 so 1 *10 is 10 are we expected to see 10 in rest of elements and if found return true else false?
0
 
LVL 33

Accepted Solution

by:
sarabande earned 500 total points
ID: 41810914
these are 3 different tests and not a sequence of recursive calls

array220([1, 2, 20], 0) → true  because 2 * 10 == 20  (3rd recursive call)

array220([3, 30], 0) → true      because3 * 10 == 30  (2nd recursive call)

array220([3], 0) → false           because the array only has 1 element.

so 1 *10 is 10 are we expected to see 10 in rest of elements

the challenge is to find a pair of consecutive numbers where (left * 10 == right).

so you have to check whether the 1 was followed by 10 and if that is not the case whether you have more luck with the next pair.

Sara
0
 
LVL 7

Author Comment

by:gudii9
ID: 41811159
the challenge is to find a pair of consecutive numbers where (left * 10 == right).

above is clear. let me think
0
3 Use Cases for Connected Systems

Our Dev teams are like yours. They’re continually cranking out code for new features/bugs fixes, testing, deploying, testing some more, responding to production monitoring events and more. It’s complex. So, we thought you’d like to see what’s working for us.

 
LVL 7

Author Comment

by:gudii9
ID: 41811180
public boolean array220(int[] nums, int index) {
  if(index>nums.length-2){
    return false;
  }
if(nums[index+1]==nums[index]*10){
  return true;
}
else{
  return array220(nums,index+1);
}

}

Open in new window


above passed all tests. any improvements or alternate approaches?
0
 
LVL 7

Author Comment

by:gudii9
ID: 41811188
public boolean array220(int[] nums, int index) {
  if(index>nums.length-2){
    return false;
  }
if(nums[index]*10==nums[index+1]){
  return true;
}
else{
  return array220(nums,index+1);
}

}


/*- recursion stops with false if the index is greater or equal to array length.
- if the index is greater than 0 and nums[index] is equal to 10 times nums[index-1] 
then stop with success.
- proceed recursion by calling array220 passing the array and the index incremented 
by 1 and return the result.
*/

Open in new window


above bit refined i think
0
 
LVL 33

Expert Comment

by:sarabande
ID: 41811244
any improvements or alternate approaches?

the 'index>nums.length-2' looks a little bit clumsy.

normally, if a range of indices needs to be handled i prefer to skip the index 0 and then can use nums[index-1] and nums[index].

public boolean array220(int[] nums, int index) {
  if(index>=nums.length){
    return false;
  }
if(index > 0 && nums[index-1]*10==nums[index]){
  return true;
}
return array220(nums,index+1);

}

Open in new window


Sara
0
 
LVL 7

Author Comment

by:gudii9
ID: 41811284
sure. got it
0

Featured Post

DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Java - Why doesn't this JFrame work 3 43
C# Error - Add Failed 12 78
map related example 6 36
tomcat administrtor 12 29
This is an explanation of a simple data model to help parse a JSON feed
Although it can be difficult to imagine, someday your child will have a career of his or her own. He or she will likely start a family, buy a home and start having their own children. So, while being a kid is still extremely important, it’s also …
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole…
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.

895 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

Need Help in Real-Time?

Connect with top rated Experts

14 Experts available now in Live!

Get 1:1 Help Now