C語言拆分雙向連結串列程式

建立一個雙向連結串列，並將此雙向連結串列中的資料項拆分成兩個雙向連結的範例程式，將以下程式碼儲存到一個原始檔中：split_doubly_linked_list.c， 如下所示 -

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

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

struct node {
    int data;
    struct node *prev;
    struct node *next;
};

struct node *list = NULL;
struct node *list_last = NULL;

struct node *even = NULL;
struct node *even_last = NULL;

struct node *odd = NULL;
struct node *odd_last = NULL;

struct node *current = NULL;

//Create Linked List
void insert(int data) {
    // Allocate memory for new node;
    struct node *link = (struct node*) malloc(sizeof(struct node));

    link->data = data;
    link->prev = NULL;
    link->next = NULL;

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

    current = list;

    // move to the end of the list
    while (current->next != NULL)
        current = current->next;

    // Insert link at the end of the list
    current->next = link;
    list_last = link;
    link->prev = current;
}

//display the list
void print_backward(struct node *head) {
    struct node *ptr = head;

    printf("\n[last] <=>");
    //start from the beginning
    while (ptr != NULL) {
        printf(" %d <=>", ptr->data);
        ptr = ptr->prev;
    }

    printf(" [head]\n");
}

//display the list
void printList(struct node *head) {
    struct node *ptr = head;

    printf("\n[head] <=>");
    //start from the beginning
    while (ptr != NULL) {
        printf(" %d <=>", ptr->data);
        ptr = ptr->next;
    }

    printf(" [last]\n");
}

void split_list() {

    // Allocate memory for new node;
    struct node *listp;
    struct node *link;
    struct node *current;

    listp = list;

    while (listp->next != NULL) {
        struct node *link = (struct node*) malloc(sizeof(struct node));

        link->data = listp->data;
        link->prev = NULL;
        link->next = NULL;

        if (listp->data % 2 == 0) {
            if (even == NULL) {
                even = link;
                even_last = link;
                listp = listp->next;
                continue;
            }
            else {
                current = even;
                while (current->next != NULL) {
                    current = current->next;
                }

                // Insert link at the end of the list
                current->next = link;
                even_last = link;
                link->prev = current;
                listp = listp->next;
            }
        }
        else {
            if (odd == NULL) {
                odd = link;
                odd_last = link;
                listp = listp->next;
                continue;
            }
            else {
                current = odd;

                while (current->next != NULL) {
                    current = current->next;
                }
                // Insert link at the end of the list
                current->next = link;
                odd_last = link;
                link->prev = current;
                listp = listp->next;
            }
        }
    }
    // Lets handle the last node
    if (listp != NULL) {
        link = (struct node*) malloc(sizeof(struct node));

        link->data = listp->data;
        link->prev = NULL;
        link->next = NULL;

        if (listp->data % 2 == 0) {
            current = even;

            while (current->next != NULL) {
                current = current->next;
            }

            // Insert link at the end of the list
            current->next = link;
            even_last = link;
            link->prev = current;
        }
        else {
            current = odd;

            while (current->next != NULL) {
                current = current->next;
            }
            // Insert link at the end of the list
            current->next = link;
            odd_last = link;
            link->prev = current;
        }

    }
}


int main() {
    int i;

    for (i = 1; i <= 10; i++)
        insert(i);

    printf("Complete List : ");
    printList(list);

    printf("List in reverse: ");
    print_backward(list_last);

    split_list();

    printf("\nAfter splitting list - \n");

    printf("Even : ");
    printList(even);

    printf("Odd  : ");
    printList(odd);

    printf("\nSplitted lists in reverse - \n");

    printf("Even : ");
    print_backward(even_last);

    printf("Odd  : ");
    print_backward(odd_last);

    return 0;
}

執行上面程式，得到以下結果 -

Complete List :
[head] <=> 1 <=> 2 <=> 3 <=> 4 <=> 5 <=> 6 <=> 7 <=> 8 <=> 9 <=> 10 <=> [last]
List in reverse:
[last] <=> 10 <=> 9 <=> 8 <=> 7 <=> 6 <=> 5 <=> 4 <=> 3 <=> 2 <=> 1 <=> [head]

After splitting list -
Even :
[head] <=> 2 <=> 4 <=> 6 <=> 8 <=> 10 <=> [last]
Odd  :
[head] <=> 1 <=> 3 <=> 5 <=> 7 <=> 9 <=> [last]

Splitted lists in reverse -
Even :
[last] <=> 10 <=> 8 <=> 6 <=> 4 <=> 2 <=> [head]
Odd  :
[last] <=> 9 <=> 7 <=> 5 <=> 3 <=> 1 <=> [head]