动手实现 数据结构 之 “双向链表”

C 语言方式实现了 双向链表的 

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#include <stdio.h>#include <stdlib.h>typedef int bool;typedef struct Node {    struct Node * front;    struct Node * back;    int data;}Node;typedef struct List {    struct Node * begin;// 第一个元素    struct Node * end;  // 最后一个元素的后一个元素}List;// 使用链表前必须 调用Initvoid Init(struct List * list) {    struct Node * node = (struct Node*)malloc(sizeof(struct Node));    node->front = NULL;    node->back = NULL;    // 当链表为空时预留一个元素（只是为了增加效率和设计上的方便）    list->begin = node;    list->end = list->begin;}bool IsEmpty(struct List * list) {    return list->end == list->begin;}// 在链表中从头到尾 查找第一个数据为data 的节点struct Node* SearchList(struct List * list, int data) {    for(struct Node* p=list->begin; p != list->end; p=p->back) {        if(p->data == data) return p;    }    return NULL;}void PushFront(struct List * list, int data) {    struct Node * node = (struct Node*)malloc(sizeof(struct Node));    node->data = data;        node->front = NULL;    node->back = list->begin;        list->begin->front= node;    list->begin = node;}void PushBack(struct List * list, int data) {    list->end->data = data;        struct Node * node = (struct Node*)malloc(sizeof(struct Node));    node->back = NULL;        node->front = list->end;    list->end->back = node;    list->end = node;}int PopFront(struct List * list) {    int result = list->begin->data;    struct Node * p = list->begin;    list->begin = list->begin->back;    list->begin->front = NULL;    free(p);    return result;}int PopBack(struct List * list) {    struct Node * last = list->end->front;    int result = last->data;        struct Node * p = list->end;    last->back = NULL;    list->end = last;    free(p);    return result;}// 在节点 pos 后插入一个节点 数据为datavoid InsertNodeTo(struct List * list, struct Node* pos, int data) {    struct Node * node = (struct Node*)malloc(sizeof(struct Node));    node->data = data;        node->front = pos;    node->back = pos->back;        pos->back = node;    node->back->front = node;        if(list->end == pos)        list->end = pos;}// 删除 list 中 pos 节点 （end 前一个元素是最后一个元素，不能删除 end 因为 end 是辅助节点不用于存储）void RemoveNodeFrom(struct List * list, struct Node* pos) {    if(pos == list->begin) PopFront(list);    else if(pos == list->end->front) PopBack(list);    else {        pos->front->back = pos->back;        pos->back->front = pos->front;        free(pos);    }}void PrintList(struct List * list) {    for(struct Node* p=list->begin; p != list->end; p=p->back) {        printf("%d  ", p->data);    }    printf("\n");}// 使用完需要使用Destroy将内存释放void Destroy(struct List * list) {    struct Node* back;    for(struct Node* p=list->begin; p != list->end; p=back) {        back = p->back;        free(p);    }    if(list->end != NULL) free(list->end);}int main(void){    List list;    Init(&list);        PushBack(&list, 1);    PushBack(&list, 2);    PushBack(&list, 3);    PushBack(&list, 4);    PushBack(&list, 5);        PushFront(&list, 0);        Node * pos = SearchList(&list, 3);        InsertNodeTo(&list, pos, 9);        PrintList(&list);        printf("Pop front %d\n", PopFront(&list));        printf("Pop back %d\n", PopBack(&list));        RemoveNodeFrom(&list, list.begin);        struct Node* p;    for(p=list.end->front; p!=list.begin; p=p->front) {        printf("%d  ", p->data);    }    printf("%d\n", p->data);        Destroy(&list);    return 0;}