이중 연결리스트

#include <stdio.h> #include <stdlib.h> #include <conio.h> typedef struct _dnode { int key; struct _dnode *next; struct _dnode *prev; }DNODE; DNODE *start = NULL; DNODE *cur = NULL; void insert(void); void print(void); void del_node(void); void delete_node(void); void main() { int no; while(1) { system("cls"); puts("*** MENU ***"); puts("1. INSERT"); puts("2. PRINT"); puts("3. DELETE"); puts("4. END"); printf("choice : "); scanf("%d", &no); fflush(stdin); switch(no) { case 1 : insert(); break; case 2 : print();break; case 3 : delete_node(); break; //del_node(); break; case 4 : exit(1); } getch(); } } void insert(void) { DNODE* newnode; if(cur != NULL) printf("\n\tcur->key : %d\n", cur->key); newnode = (DNODE*)malloc(sizeof(DNODE)); printf("\n\tInput number : "); scanf("%d", &newnode->key); fflush(stdin); newnode->next = newnode->prev = NULL; if(start == NULL) { start = newnode; cur = start; printf("\n\t배열이 비어있을 때 삽입...\n"); return; } if(cur->key < newnode->key) // NEXT... { while(cur->next != NULL) { // cur(5) [newnode(8)] cur->next(10) cur->next->next if(cur->next->key > newnode->key) { newnode->next = cur->next; newnode->prev = cur; cur->next->prev = newnode; cur->next = newnode; printf("\n\tNEXT... 중간삽입...\n"); return; } cur = cur->next; } // cur(10) [newnode(15)] NULL newnode->prev = cur; cur->next = newnode; printf("\n\tNEXT... 맨 마지막삽입...\n"); } else // PREV... { while(cur->prev != NULL) { // 3(cur->prev) [5(newnode)] 6(cur) 10 12 if(cur->prev->key < newnode->key) { newnode->next = cur; newnode->prev = cur->prev; cur->prev->next = newnode; cur->prev = newnode; printf("\n\tPREV... 중간삽입...\n"); return; } cur = cur->prev; } // NULL [newnode(2)] cur, start(3) newnode->next = cur; cur->prev = newnode; start = newnode; printf("\n\tPREV... 맨 앞삽입...\n"); } } void print(void) { DNODE* cur; if(start == NULL) { printf("\n\t연결리스트가 구성되어있지 않아 출력할 수 없습니다...\n"); return; } printf("\n\t< 오름차순 >\n"); cur = start; while(cur->next != NULL) { printf("%d -> ", cur->key); cur = cur->next; } printf("%d\n", cur->key); printf("\n\t< 내림차순 >\n"); while(cur->prev != NULL) { printf("%d -> ", cur->key); cur = cur->prev; } printf("%d\n", cur->key); } void del_node(void) { int no; DNODE *del; if(start == NULL) { printf("\n\t연결리스트가 구성되어있지 않아 삭제할 수 없습니다...\n"); return; } printf("\n\tCUR->KEY : %d\n", cur->key); printf("\n\t삭제할 정수 : "); scanf("%d", &no); fflush(stdin); if(cur->key == no) { // del // cur->prev cur cur->next del = cur; if(cur->next != NULL && cur->prev != NULL) { cur->prev->next = cur->next; cur->next->prev = cur->prev; cur = cur->next; } else if(cur->next == NULL && cur->prev != NULL) { cur->prev->next = NULL; cur = cur->prev; } else if(cur->next != NULL && cur->prev == NULL) { cur->next->prev = NULL; start = start->next; cur = cur->next; } else //cur->next == NULL && cur->prev == NULL start = cur = NULL; printf("\n\tCUR... delete... [%d]\n", del->key); free(del); } else if(cur->key < no) // NEXT... { while(cur->next != NULL) { // del del->next // 5(cur) 8(cur->next) 10(cur->next->next) 12 if(cur->next->key == no) { del = cur->next; cur->next = del->next; if(del->next != NULL) del->next->prev = cur; printf("\n\tNEXT... delete... [%d]\n", del->key); free(del); return; } cur = cur->next; } printf("\n\t입력하신 정수 [%d]는 존재하지 않습니다...\n", no); } else // PREV... { while(cur->prev != NULL) { // del->prev del // 3(cur->prev->prev) 5(cur->prev) 8(cur) 10 if(cur->prev->key == no) { del = cur->prev; if(del->prev != NULL) del->prev->next = cur; else start = start->next; cur->prev = del->prev; printf("\n\tPREV... delete... [%d]\n", del->key); free(del); return; } cur = cur->prev; } printf("\n\t입력하신 정수 [%d]는 존재하지 않습니다...\n", no); } } void delete_node(void) { int no; DNODE *del; if(start == NULL) { printf("\n\t연결리스트가 구성되어있지 않아 삭제할 수 없습니다...\n"); return; } printf("\n\tCUR->KEY : %d\n", cur->key); printf("\n\t삭제할 정수 : "); scanf("%d", &no); fflush(stdin); del = cur; if(cur->key < no) { while(cur != NULL && cur->key != no) cur = cur->next; } else if(cur->key > no) { while(cur != NULL && cur->key != no) cur = cur->prev; } if(cur == NULL) { printf("\n\t입력하신 정수 [%d]는 존재하지 않습니다...\n", no); cur = del; return; } // del->prev del del->next // cur->prev cur cur->next del = cur; if(del->prev != NULL) { del->prev->next = del->next; cur = cur->prev; } else { start = start->next; cur = cur->next; } if(del->next != NULL) del->next->prev = del->prev; printf("\n\tdelete... [%d]\n", del->key); free(del); }