Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

array220 challenge

Posted on 2016-09-21
8
Medium Priority
?
119 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 35

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 35

Accepted Solution

by:
sarabande earned 2000 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
VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

 
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
 
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 35

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

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!

Question has a verified solution.

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

The SignAloud Glove is capable of translating American Sign Language signs into text and audio.
This article will show how Aten was able to supply easy management and control for Artear's video walls and wide range display configurations of their newsroom.
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.
Suggested Courses

579 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