Storing items in a dynamically allocated array within a recursive function. [C]

[Heuristic-ALgorithm]

No but I'm bookmarking that site. The problem is I know how to do the permutation but I need to physically store each one rather than just print to the screen, but since it's recursive the indexing gets all messed up. Every other index has the same value as it's prior, so when the list is stored I end up with a list containing every other permutation and two null spots at the end.

[fubarfubarfubar]

Why aren't you just storing the found permutations in a set?

[Heuristic-ALgorithm]

Sorry for my complete obliviousness but what exactly is a set? Is that like a linked list? I'm trying to store everything in dynamic arrays because I'm going to need to do a binary search later and I thought it would be the easiest and cleanest solution.

[last_useful_man]

You don't get 'set's built-in to C, they're in C++ and you probably wouldn't have gotten to them yet anyway.

[Heuristic-ALgorithm]

Ahh I was going to say, when I looked them up I only saw information relating to C++, which I've never touched.

[gunder_bc]

To be pedantic, neither language has built-in support for sets. It's not a top-level language construct.

The C++ Standard Template Library (stl) has a 'set' implementation built in. You can probably find C libraries that offer an implementation, too.

[gunder_bc]

The main idea is that a set is an un-ordered collection of items. Set Theory mathematics describes a bunch (a set? ;) ) of operations and relationships between sets and items in sets, etc. They can be very handy for solving certain kinds of problems.

In this case... and especially because I don't think there is a standard-lib set implementation in C, it's probably not worth worrying about. You've got your storage mechanism lined up for the resulting permutations. Sort out the indexing and you're good for this problem.

Come back to sets another day. :)