线性表之双向链表
不是存放在连续的内存空间,链表中的每个节点的next都指向下一个节点,每个节点的before都指向前一个节点,最后一个节点的下一个节点是NULL。
真实的第一个节点是头节点,头节点不存放数据,单纯为了编写程序方便。但是下面注释里写的【第一个节点】的含义是头节点的下一节点,也就是真实存放数据的第一个节点。
下面的代码实现了以下功能
| 函数 | 功能描述 |
|---|---|
| push_back | 从链表的最后插入节点 |
| push_front | 从链表的起始插入节点 |
| show_list | 打印出链表里每个节点的值 |
| pop_back | 删除链表最后一个节点 |
| pop_front | 删除链表起始节点 |
| insert_val | 在合适的位置插入一个节点; 比如原来的链表:1->3->NULL,当要插入的节点的值为2的时候,就会在1和3之间插入这个节点,插入后的链表:1->2->3->NULL |
| find | 查找指定的节点 |
| length | 返回链表中节点的个数 |
| delete_val | 删除指定的节点 |
| sort | 排序,重新排列节点 |
| resver | 按倒序,重新排列节点 |
| clear | 释放除了头节点之外的所有节点所占用的内存空间 |
| destroy | 释放所有节点的所占用的内存空间,包括头节点 |
shuangnode.h
#ifndef __SHUANGNODE__#define __SHUANGNODE__#include <stdio.h>#include <malloc.h>#include <assert.h>#include <memory.h>#include <stdbool.h>#define ElemType inttypedef struct Node{
ElemType data; struct Node* before;
struct Node* next;}Node;typedef struct NodeList{
Node* first;
Node* last; size_t size;
}NodeList;void init(NodeList*);void push_back(NodeList*, ElemType);void push_front(NodeList*, ElemType);void pop_back(NodeList*);void pop_front(NodeList*);void show_list(NodeList*);void insert_val(NodeList*, ElemType);Node* find(NodeList*, ElemType);void delete_val(NodeList*, ElemType);void sort(NodeList*);void sort1(NodeList*);void resver(NodeList*);void resver1(NodeList*);void resver2(NodeList*);void clear(NodeList*);void destroy(NodeList*);#endifshuangnode.c
#include "shuangnode.h"void init(NodeList* list){
list->first = (Node*)malloc(sizeof(Node));
list->last = list->first;
list->last->next = NULL;
list->size = 0;
}
Node* create_node(ElemType val){
Node* node = (Node*)malloc(sizeof(Node));
assert(NULL != node);
node->data = val;
node->before = NULL;
node->next = NULL; return node;
}void push_back(NodeList* list, ElemType val){
Node* p = create_node(val);
p->before = list->last;
p->next = NULL;
list->last->next = p;
list->last = p;
list->size++;
}void push_front(NodeList* list, ElemType val){
Node* p = create_node(val); //设置p的before和next
p->before = list->first;
p->next = list->first->next; //第一次添加节点的时候要移动未指针
if(NULL == list->first->next){
list->last = p;
} //不是第一次添加节点的时候,要把原第一个节点的before指向,新添加的节点
else{
list->first->next->before = p;
} //设置头指针的next节点
list->first->next = p;
list->size++;
}void show_list(NodeList* list){
Node* tmp = list->first->next;
while(tmp != NULL){
printf("%d->", tmp->data);
tmp = tmp->next;
} printf("NULL\n");
}void pop_back(NodeList* list){
if(list->size == 0)return;
free(list->last); //让尾指针的next指向NULL
list->last->before->next = NULL; //让尾指针指向原尾节点的前一个节点
list->last = list->last->before; list->size--;
}void pop_front(NodeList* list){ if(list->size == 0)return; free(list->first->next); //就剩一个节点的时候,要移动尾指针。因为list->first->next已经为NULL,下面的list->first->next->before就会在执行时候崩掉,所以要return掉
if(list->first->next == list->last){ list->last = list->first; list->last->next = NULL; list->size--; return;
}
//头指针的next指向第二个节点
list->first->next = list->first->next->next; //第二个节点的before指向头节点
list->first->next->before = list->first;
list->size--;
}void insert_val(NodeList* list, ElemType val){
Node* n = create_node(val);;
Node* p = list->first;
while(p->next != NULL && val > p->next->data){
p = p->next;
} //第一次加节点,或者,最后一个节点也没有给的值大的时候
if(NULL == p->next){
n->next = NULL;
n->before = list->last;
list->last->next = n;
list->last = n;
list->size++;
return;
} //新节点的next指向原节点的下一个节点
n->next = p->next; //原节点的next指向新节点,注意这句的位置必须在上句的下面
p->next = n; //新节点的下一个节点的before指向新节点
n->next->before = n; //新节点的before指向原节点
n->before = p; list->size++;
}//寻找给定值的节点的位置Node* find(NodeList* list, ElemType val){
if(list->size == 0)return NULL;
Node* p = list->first;
while(p->next != NULL && p->next->data != val){
p = p->next;
} if(NULL == p->next){
return NULL;
} printf("%d is found\n", p->next->data);
return p->next;
}//寻找给定值的节点的前一个节点的位置Node* find1(NodeList* list, ElemType val){
if(list->size == 0)return NULL;
Node* p = list->first;
while(p->next != NULL && p->next->data != val){
p = p->next;
} if(NULL == p->next){
return NULL;
} printf("%d is found\n", p->next->data);
return p;
}void delete_val(NodeList* list, ElemType val){
Node* p = find1(list, val);
if(NULL == p) return; free(p->next); //删除的节点是尾节点的时候,要移动last
if(p->next == list->last){
list->last = p;
p->next = NULL;
list->size--;
return;
}
p->next->next->before = p;
p->next = p->next->next;
list->size--;
}void sort(NodeList* list){
if(list->size == 1 || list->size == 0)return; //p为第一个节点
Node* p = list->first->next; //t是空白list,往t里加节点
Node* t = list->first;
list->last = list->first;
list->last->next = NULL;
size_t sz = list->size;
Node* tmp;
while(sz-- > 0){ //p的next会被改变,所以提前保存
tmp = p->next;
while(t->next != NULL && p->data > t->next->data){
t = t->next;
} //t为first,或者t为last,都是尾插
if(t->next == NULL){
t->next = p;
p->next = NULL;
p->before = t;
list->last = p;
} else{
p->next = t->next;
t->next->before = p;
t->next = p;
p->before = t;
}
p = tmp;
t = list->first;
}
}void resver(NodeList* list){
if(list->size == 1 || list->size == 0)return; //第一个节点
Node* head = list->first->next; //第二个节点
Node* second = head->next; //head就是last,所以要head->next = NULL;
list->last = head;
list->last->next = NULL;
Node* tmp; while(second != NULL){ //必须保存second的next,因为下面的代码,会改变second的next
tmp = second->next;
second->next = list->first->next;
list->first->next->before = second;
list->first->next = second;
second->before = list->first;
second = tmp;
}
}void clear(NodeList* list){
Node* p = list->first->next;
while(p != NULL){
free(p);
p = p->next;
} list->last = list->first;
list->last->next = NULL;
list->size = 0;
}void destroy(NodeList* list){
Node* p = list->first;
while(p != NULL){
free(p);
p = p->next;
} list->size = 0;
}shuangnodemain.c
#include "shuangnode.h"int main(){
NodeList list;
init(&list); int select = 1;
ElemType item;
Node* node = NULL; while(select){
printf("*****************************************\n");
printf("*** [1] push_back [2] push_front ***\n");
printf("*** [3] show_list [4] pop_back ***\n");
printf("*** [5] pop_front [6] insert_val ***\n");
printf("*** [7] find [8] length ***\n");
printf("*** [9] delete_val [10] sort ***\n");
printf("*** [11] sort [12] resver ***\n");
printf("*** [13] [14] clear ***\n");
printf("*** [0] quit [15*]destroy ***\n");
printf("*****************************************\n");
printf("请选择:>"); scanf("%d", &select);
if(0 == select)
break;
switch(select){
case 1:
printf("请输入要插入的数据,以-1结束>\n");
while(scanf("%d",&item) && item != -1){
push_back(&list, item);
}
show_list(&list); break;
case 2:
printf("请输入要插入的数据,以-1结束>\n");
while(scanf("%d", &item) && item != -1){
push_front(&list, item);
}
show_list(&list); break; case 3:
show_list(&list); break; case 4:
pop_back(&list);
show_list(&list); break; case 5:
pop_front(&list);
show_list(&list); break; case 6:
printf("请输入要插入的数据>\n");
scanf("%d",&item);
insert_val(&list, item);
show_list(&list); break; case 7:
printf("please enter what you shoule find out>\n");
scanf("%d",&item);
node = find(&list, item); if(node == NULL){
printf("can not find %d\n", item);
} break;
case 8:
printf("length is %ld\n", list.size);
break;
case 9:
printf("please enter what you want to delete>\n");
scanf("%d",&item);
delete_val(&list, item);
show_list(&list); break; case 10: // sort(&list);
//show_list(&list);
break; case 11:
sort(&list);
show_list(&list); break; case 12:
resver(&list);
show_list(&list); break; case 13:
resver(&list);
show_list(&list); break; case 14:
clear(&list);
show_list(&list); break; case 15:
destroy(&list); break; default: break;
}
}
destroy(&list);
}原文链接:https://www.cnblogs.com/xiaoshiwang/p/9237129.html
作者:小石王
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