Sorting without arrays

Question

Imagine that you have ten different variables with decimal values and you have to sort them from lowest to highest. I am familiar with the different sorting alogorithms using different programming languages, but in this case, I have to build the algorithm in an end-user application that just allow to enter some especific constructions: it allows to use "for", "while", "if", but nothing to do with arrays, it means, it cannot deal with something like a[i] where "a" is an array. Please, can anybody give me a clue?. Thanks a lot!

Your problem is not clear. Firstly, if you cannot do write on `a`, you cannot do inplace sorting. You can make a copy of it, sort it and return that array. Or if you have to find the min/ max element as the input is given to you, use `heap` — vish4071, Apr 26 '16 at 07:46
So you are trying to sort in a language that doesn't support arrays? — M Oehm, Apr 26 '16 at 07:50
This solves your problem http://stackoverflow.com/questions/25070577/sort-4-numbers-without-array . Extend 4 with your number. — Karthikeyan Gopall, Apr 26 '16 at 07:54
Thanks. Yes, the problem is that I have to deal with an application that allows you to create scripts but these scripts are not provided with the usual elements/instructions that you can use when you use a full language. So, in that sense, it is like I use a language that doesn't support arrays. — chufabit, Apr 26 '16 at 07:56
Thanks a lot @KarthikeyanGopall, I was thinking something like that, but in my case it is a 10-variables problem, so writing the code can be a pain. I just wondering if it is possible to deal with it in a more efficient way. — chufabit, Apr 26 '16 at 07:59
Definitely, I think I can deal with the problem using the solution by @KarthikeyanGopall, I have to use 32 comparators, that is a tolerable pain : ) Thanks again! — chufabit, Apr 26 '16 at 08:09

score 1 · Answer 1 · answered Apr 26 '16 at 08:00

1

you mean something like this ?

c++ code :

void sort_4(int *a1, int *a2, int *a3, int *a4)
{
  if (a1 == NULL) return;
  if (a2 == NULL) return;
  if (*a2 < *a1) swap(*a1, *a2);
  sort_5(a1, NULL, NULL, NULL);
  if (a3 == NULL) return;
  if (*a2 < *a3) swap(*a2, *a3);
  sort_5(a1, a2, NULL, NULL);
  if (a4 == NULL) return;
  if (*a4 < *a3) swap(*a3, *a4);
  sort_5(a1, a2, a3, NULL);
}

you can expand it to 10 elements by copy-and-paste or by a code generation script.

answered Apr 26 '16 at 08:00

Ke Yang

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1
6

Thanks @Ke Yang, but in this case I cannot invoke a method, no recursively way. – chufabit Apr 26 '16 at 08:07
then you might need to use a large amount of code to implement the sort. for example, about 50 times compare for 10 elements using bubble sort. You can write a script to generate the code. – Ke Yang Apr 26 '16 at 08:29

Jim Mischel · Answer 2 · 2016-04-26T14:30:40.513

Well, you could hard-code a bubble sort. For example, imagine you have 10 variables, a, b, c, d, e, f, g, h, i, j:

for (int x = 0; x < 9; ++x)
{
    if (a > b) swap(a,b);
    if (b > c) swap(b,c);
    if (c > d) swap(c,d);
    if (d > e) swap(d,e);
    if (e > f) swap(e,f);
    if (f > g) swap(f,g);
    if (g > h) swap(g,h);
    if (h > i) swap(h,i);
    if (i > j) swap(i,j);
}

That's not terribly efficient, but you're not going to notice the inefficiency in a UI application that only has 10 or so items. You can make it slightly more efficient by nesting the conditionals:

    if (x < 9)
    {
       if (a > b) swap(a,b);
       if (x < 8)
       {
           if (b > c) swap(b,c);
           if (x < 7)
           {
               ....

But that gets unwieldy in a hurry and again the small efficiency it gives you won't be noticed for such a small list.

Sorting without arrays

2 Answers2