// CList.c - By Michael G. Workman
//
// This C console application builds a list and outputs the results of the list
// then times the results
//
// This application is freely distributable under terms of MIT open source license

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

// struct type for linked list
struct Integers
{
    unsigned int nIntNumber;
    struct Integers* next;
    struct Integers* previous;
};

// head and last nodes
struct Integers* head = NULL;
struct Integers* last = NULL;

// to keep track of the current node pointed to 
struct Integers* current = NULL;

// Create Linked List
void insert(int data) {

    // Allocate memory for new node
    struct Integers* node = malloc(sizeof(struct Integers));

    node->nIntNumber = data;
    node->previous = NULL;
    node->next = NULL;

    // If head is empty, create new list
    if (head == NULL) {
        head = node;
        last = node;
        return;
    }

    // start at the end of the list
    if (last != NULL)
    {
        current = last;
    }
    else
    {
        current = head;
    }

    // Insert link at the end of the list
    current->next = node;
    last = node;
    node->previous = current;
}

// output the list
void outputList() {
    
    // start at first node in list
    struct Integers* ptr = head;

    // output the contents of the list
    while (ptr != NULL) {
        printf("%d \n", ptr->nIntNumber);
        ptr = ptr->next;
    }
}


int main()
{    
    // start timing
    clock_t start = clock();
    
    // loop through total number of elements adding each integer with each iteration
    int i;
    for (i = 0; i < 100000; i++)
    {
        insert(i);
    }

    // output the contents of the list
    outputList();

    // stop timing
    clock_t stop = clock();

    // calculate time in seconds
    double timeSeconds = ((double) stop - start) / (double) CLOCKS_PER_SEC;

    // output results
    printf("C time to build and display list: %f seconds\n", timeSeconds);
    printf("Number of elements: %d \n\n", i);

    return 0;
}