Question

I have the following struct for a linked list:

struct Node {
    int type;
    int otherInfo;
    Node * next;
}

I want to create a sorted (eventually) linked list that keeps track of how many times each “type” appears. An example node would be:

struct Node2 {
    int type;
    int frequency;
    //A linked list to keep track of the "otherInfo"
    Node2 * next;
}

My current algorithm is O(n^2), which is unreasonable because the original linked list can sometimes have over 30,000 elements. Is there a more efficient way to do this?

Note: type can be pretty much any positive integer, so I can’t simply make an static array with type as the indexes.

EDIT: The frequency list does not have to be a linked list. I gave that as an example. Later on in the program, I sort the frequency list using a heap. I just need to be able to traverse the frequency list later.

Answer 1

Sounds like what you really need is a map or a basic binary search tree. The key type will be your type value, and the value type will hold your frequency.