Question

I am having big troubles representing a sparse matrix in C with a multi-list, as my university teacher asked.

For what I understood there are several kinds of lists:

• The main one contains a pointer to next row and column
• One for column and rows
• One of elements.

Any help on how to implement this would be greatly appreciated.

Answer 1

( I will explain how can you represent the picture if that is what are you asking )
From your picture I understand that you have 3 types of nodes and some rules:

• a) one for the number of rows and columns ( with 2 pointer )
• b) one for the size of the matrix ( 2 pointers and the witdh and
  height)
• c) one with the value of an element that is not zero ( with 2
  pointers, the colum value and the row value of the element and the
  element)

Rules:

1. The b) element has a pointer to the first row element and first
   column element
2. Each row element has a pointer to the next row element ( the last has a pointer
   to the b) element )
3. Each colum element has a pointer to the next colum element and the last
   has a pointer to the b) element
4. each row has the second pointer pointing the first c) element on their row
5. each colum has the second pointer pointing to the first c) element on their
   colum
6. each element points to: the next c) element on their row and the next c) element on their column ( if there is no next element on the row just point to the row element, and if there is no next element on the column just point to the column element)

For each rule if you can’t apply you just skip it and leave that pointer null
Hope it helped.

You can create some custom linked lists and just apply the rules
Here you have a simple tutorial