[C] Macierz rzadka

#include <stdio.h>
#include <stdlib.h>

#define SIZE_X 4
#define SIZE_Y 3


struct Point
{
    double value;
    int x;
    int y;
    struct Point *next;
};


void addElement(struct Point **headPointer, double matrixValue, int matrixX, int matrixY)
{
    struct Point *pointer;
    pointer = *headPointer;

    if (matrixValue != 0)
    {
        if(pointer == NULL)
        {
            pointer = (struct Point*)malloc(sizeof(struct Point));
            pointer->value = matrixValue;
            pointer->x = matrixX;
            pointer->y = matrixY;
            pointer->next = NULL;
            *headPointer = pointer;
        }
        else
        {
            while (pointer->next != NULL)
            {
                pointer = pointer->next;
            }
            pointer->next = (struct Point*)malloc(sizeof(struct Point));
            pointer = pointer->next;
            pointer->value = matrixValue;
            pointer->x = matrixX;
            pointer->y = matrixY;
            pointer->next = NULL;
        }
    }


}


void showAll(struct Point *head)
{
    if (head != NULL)
    {
        printf("%lf (%d,%d)\n", head->value, head->x, head->y);

        while(head->next != NULL)
        {
            head = head->next;
            printf("%lf (%d,%d)\n", head->value, head->x, head->y);
        }
    }
}


void findMaxMin(struct Point *head, struct Point **max, struct Point **min)
{
    if (head != NULL)
    {
        *max = head;
        *min = head;

        while (head->next != NULL)
        {
            head = head->next;
            if (head->value > (*max)->value)
            {
                *max = head;
            }
            if (head->value < (*min)->value)
            {
                *min = head;
            }
        }
    }
}


int main()
{
    int i, j;
    double matrix[SIZE_X][SIZE_Y];
    struct Point *head, *maxElement, *minElement;

    head = NULL;
    maxElement = NULL;
    minElement = NULL;

    // inicjalizacja macierzy
    for(i = 0; i < SIZE_X; i++)
    {
        printf("Wprowadz elementy %d wiersza (%d):", (i+1), SIZE_Y);
        for(j = 0; j < SIZE_Y; j++)
        {
            scanf("%lf", &matrix[i][j]);
        }
    }

    // dodawanie elemntow macierzy rzadkiej
    for(i = 0; i < SIZE_X; i++)
    {
        for(j = 0; j < SIZE_Y; j++)
        {
            addElement(&head, matrix[i][j], (i+1), (j+1));
        }
    }

    showAll(head);

    findMaxMin(head, &maxElement, &minElement);
    printf("\n\nMin: %lf (%d,%d)\n", minElement->value, minElement->x, minElement->y);
    printf("Max: %lf (%d,%d)\n", maxElement->value, maxElement->x, maxElement->y);


    return 0;
}