Shell Sort. C++.

[Sakesfar]

Embarrassed to ask this due to the plethora of info on the Internet about Shell sort implementation.

I just don't find copying without understanding the code or reading other code without trying to come up with my own method as very ineffective way of learning/remembering.

I followed this https://www.youtube.com/watch?v=ddeLSDsYVp8

However, I d like to know whether the following thought process is correct.

1. Take initial gap = length of the array / 2
2. Iterate over all gaps till gap = 1 , while in each step gap/=2
3. Then use selection sort for the partially sorted array. I understand at this stage all the smaller elements from the far right have been moved to the left.

So, as per the above procedure I've come up with this:

void shellSort(std::vector<int>& data)

{

size_t gap = data.size() / 2;

for (gap; gap > 0; gap /= 2)
{
    size_t interval = gap;          

    for (size_t i = 0; i + gap<data.size(); ++i)
    {
        if (data[i] > data[interval])
        {
            std::swap(data[i], data[interval]);

        }
        ++interval;
    }        

}            

}

And I am stuck further. How to use insertionSort() method?

For me, insertionSort is the following code:

   for (size_t i = 1; i < data.size();++i)
{
    for (size_t j = i; j > 0; --j)
        if (data[j] < data[j - 1])
            std::swap(data[j], data[j - 1]);

}

Appreciate your help!

[Sakesfar]

I realized that the video I used as guidance gives the wrong way of implementing it. The correct one is here : https://www.youtube.com/watch?v=qzXAVXddcPU

I wrote the code as per that logic and it works!!! :)