How to replace with loop in c++

Question

I have a piece of code like this:

#include <iostream>
using namespace std;

int shellSortAscendent(int arr[], int N)
{
    for (int gap = N / 2; gap > 0; gap /= 2) {
        for (int i = gap; i < N; i += 1) {
            //sort sub lists created by applying gap
            int temp = arr[i];
            int j;
            for (j = i; j >= gap && arr[j - gap] > temp; j -= gap)
                arr[j] = arr[j - gap];
            arr[j] = temp;
        }
    }
    return 0;
}

Here's how I tried to do it :

int shellSortAscendent(int arr[], int N)
{
    int gap = N / 2;

    do {
        gap /= 2;
        int i = gap;
        do {
            int temp = arr[i];
            int j;
            j = i;
            i += 1;

            do {
                j -= gap;

            } while (j >= gap && arr[j - gap] > temp);
            arr[j] = arr[j - gap];
            arr[j] = temp;
        } while (i < N);
    } while (gap > 0);
    return 0;
}

But the result is incorrectly sorted and some numbers are duplicated. Please help me understand the reason

Note that `do`/`while` will always execute the body at least once, even if the condition would be `false` immediately. A `while` loop can more closely resembles a `for` loop. — François Andrieux, Oct 27 '20 at 19:20
You're performing `gap /= 2` at the beginning of your loop instead of at the end of it. — Nathan Pierson, Oct 27 '20 at 19:20
why do you want to replace the for loops with while? intendation aside imho the first is easier to read. If it is also correct, why change to `while` ? — 463035818_is_not_a_number, Oct 27 '20 at 19:20
@idclev463035818 to me it sounds like an assignment made up by a teacher that has no idea how to teach a language — JHBonarius, Oct 27 '20 at 19:22
@JHBonarius to me it looks like we cannot know what is OPs motivation ;) — 463035818_is_not_a_number, Oct 27 '20 at 19:22

How to replace with loop in c++

0 Answers0