C語言連線兩個迴圈連結串列程式

建立兩個迴圈連結串列，並將這兩個迴圈連結串列連線成為一個迴圈連結串列的範例程式，將以下程式碼儲存到一個原始檔中：combine_two_circular_linked_list.c， 如下所示 -

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

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

struct node *even = NULL;
struct node *odd = NULL;
struct node *list = NULL;

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

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



    if (data % 2 == 0) {
        if (even == NULL) {
            even = link;
            even->next = link;

            return;
        }
        else {
            current = even;
            while (current->next != even)
                current = current->next;

            // Insert link at the end of the list
            current->next = link;
            link->next = even;
        }
    }
    else {
        if (odd == NULL) {
            odd = link;
            odd->next = link;

            return;
        }
        else {
            current = odd;

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

            // Insert link at the end of the list
            current->next = link;
            link->next = odd;

        }
    }
}

void display(struct node *head) {
    int temp;
    struct node *ptr = head;

    if (head == NULL) {
        printf("Linked List not initialized");
        return;
    }
    else if (head->next == head) {
        printf("%d", head->data);
        return;
    }

    printf("[head] =>");

    while (ptr->next != head) {
        printf(" %d =>", ptr->data);
        ptr = ptr->next;
    }

    printf(" %d =>", ptr->data);
    printf(" [head]\n");
}

void combine() {
    struct node *elink, *olink;

    list = even;
    elink = list;

    while (elink->next != even) {
        elink = elink->next;
    }

    elink->next = odd;
    olink = odd;

    while (olink->next != odd) {
        olink = olink->next;
    }
    olink->next = even;
}

int main() {
    int i;


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

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

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

    combine();

    printf("Combined List :\n");
    display(list);



    return 0;
}

執行上面程式，得到以下結果 -

Even : [head] => 2 => 4 => 6 => 8 => 10 => [head]
Odd  : [head] => 1 => 3 => 5 => 7 => 9 => [head]
Combined List :
[head] => 2 => 4 => 6 => 8 => 10 => 1 => 3 => 5 => 7 => 9 => [head]