Doubly Linked List (DLL) 소스코드

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#include <stdio.h> #include <stdlib.h> struct node { int data; struct node *next; struct node *prev; }; struct node *head; void addToDLL(int n) { struct node *cur; cur = (struct node *)malloc(sizeof(struct node)); cur->next = cur->prev = 0; cur->data = n; // check if there is no node if (head == 0) { head = cur; return; } // find the last node { struct node *temp = head; while (temp->next != 0) { temp = temp->next; } temp->next = cur; cur->prev = temp; return; } } void showDLL() { struct node *cur = head; while (cur != 0) { printf("%d ", cur->data); cur = cur->next; } } // find the node with data n // delete it from DLL void delFromDLL(int n) { // locate the node with data n struct node *cur = head; while (cur != 0) { if (cur->data == n) { // found the node with data n break; } cur = cur->next; } if (cur == 0) // failed to find the node with n { return; } // now, cur is pointing to the node with n // case 1. cur is the first node of DLL if (cur == head) { head = head->next; free(cur); if (head != 0) { head->prev = 0; } } else if (cur->next == 0) { // case 2.cur is the last node of DLL cur->prev->next = 0; free(cur); } else // case3. cur is a middle node { // connect the previous one with the next one cur->prev->next = cur->next; // connect the next one with the previous one cur->next->prev = cur->prev; free(cur); } } // locate the node with n // add a new with with m // if direction == 1, add m mode to the next location // direction == -1, add m node to the previous location void insertToDLL(int n, int m, int direction) { // locate the node with n struct node *cur = head; while (cur != 0) { if (cur->data == n) { // found the node with n break; } cur = cur->next; } if (cur == 0) // failed to find the node with n { // thank you return; } else { // create a new node having m struct node *newbie; newbie = (struct node *)malloc(sizeof(struct node)); newbie->next = newbie->prev = 0; newbie->data = m; // case 1: if n node is the head node if (cur == head) { if (direction == -1) { // add the newbie to the previous location head = newbie; newbie->next = cur; cur->prev = newbie; return; } else { // add the newbie to the next location // case 1. cur has a next node if (cur->next != 0) { newbie->next = cur->next; newbie->prev = cur; cur->next->prev = newbie; cur->next = newbie; return; } else { // case 2. cur has no next node newbie->prev = cur; cur->next = newbie; return; } } } else if (cur->next != 0) { // case 2: cur is neither the first nor the last node. if (direction == 1) // next location { newbie->next = cur->next; newbie->prev = cur; cur->next = newbie; newbie->next->prev = newbie; return; } else // previous location { newbie->next = cur; newbie->prev = cur->prev; cur->prev = newbie; newbie->prev->next = newbie; return; } } else { // case 3. cur is the last node if (direction == 1) { // it is the same with the addtion cur->next = newbie; newbie->prev = cur; return; } else // add to the previous location { newbie->next = cur; newbie->prev = cur->prev; cur->prev = newbie; newbie->prev->next = newbie; return; } } } } int main(void) { addToDLL(1); addToDLL(2); addToDLL(3); addToDLL(4); insertToDLL(4, 10, -1); showDLL(); return 0; }