Sum of Squares of Special Elements
The task is to find the sum of the squares of all special elements in the given array. A special element is an element that is placed on the index which divides the length of the array. Let’s solve this task with a Ruby code:


In this Ruby function sum_of_specials
, we calculate the sum of the squares of the special elements. We iterate over all the indices from 1
to n
inclusive (using (1..n).each
) and for each index i
, we check if it divides n
(if n % i == 0
). If it does, we add the square of the element at that index to the sum
.
Remember, in Ruby, array indexing starts from 0
, so when we want to access an element at index i
(considering 1based indexing), we use nums[i  1]
.
Finally, we return the sum
as the result.
What is wrong with my code:
def sum_of_squares(nums) result = 0 n = nums.size
for i in (1..n)
if n % (i1) == 0
result += nums[i1]
end
end
result
end
There are two main issues with your code:
You’re using
(i1)
in theif n % (i1) == 0
condition. This leads to a problem wheni
is1
, because(i1)
becomes0
and dividing by zero is undefined. Instead, you should directly checkif n % i == 0
.In the line
result += nums[i1]
, you’re adding the value ofnums[i1]
to the result, but the problem statement requires you to add the square of the value. Therefore, you should be squaring this value before adding it to the result.
The corrected version of your code is:


This code now correctly calculates the sum of the squares of all special elements in the nums
array. It goes through each index i
from 1
to n
(inclusive) and if i
divides n
, it adds the square of the value at that index (in the array) to the result. Finally, it returns the calculated sum.
What is 1indexed integer array ?
A 1indexed integer array is an array in which the first element is considered to be at index 1, rather than the usual 0 in many programming languages such as Ruby, Python, Java, etc.
For instance, in a 0indexed array (which is most common in many programming languages), you’d access the first element with array[0]
. However, in a 1indexed array, you’d access the first element with array[1]
.
Notably, some languages, such as MATLAB or Lua, use 1indexing by default. When a problem statement mentions a 1indexed array, it means that you should consider the first element to be at index 1 for the purpose of the problem, even if the actual programming language you are using is 0indexed.
For example, if you have an array [10, 20, 30, 40]
, the first element 10
is at index 1
in 1indexed array but at index 0
in 0indexed array (like in Ruby, Python or Java).
It confused because I don’t know how to handle the 1indexed integer array. I am only familiar with 0 based starting index in array
That’s completely understandable. Many programming languages like Ruby, Python, C++, Java and more use 0based indexing. When a problem statement gives you a 1indexed array, it means that the first element is considered at index 1 for the purpose of the problem.
The simplest way to handle this is to remember to adjust your index when accessing elements. If i
is your 1based index, you access the corresponding element in a 0based language with array[i  1]
.
Let’s apply this to your sum_of_squares
function:


In the code above, to handle the 1indexed i
in Ruby (which is 0indexed), we subtract 1 when accessing the element: nums[i  1]
.
Remember, 1indexing is just a different way to conceptualize the array for a given problem. The actual implementation will depend on the characteristics of the programming language you are using.
The reason it has been given in the problem statement is that it prevents division by 0 error. Am I right?
Yes, you’re correct. One key advantage of using 1indexing in this specific problem is that it naturally prevents division by zero. The problem statement requires you to check if the array length n
is divisible by the index i
. If you were to start i
from 0 in a 0indexed array, you’d end up trying to compute n % 0
, which would result in a division by zero error. By starting with a 1indexed array (or iterating from 1 in a 0indexed language), you avoid this issue.
My corrected solution:


Key Takeaways
 Did not know the meaning of 1 indexed array. This lead to division by 0 error.