C语言如何设计前中后队列

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队列基本概念

队列是最常见的概念，日常生活经常需要排队，仔细观察队列会发现，队列是一种逻辑结构，是一种特殊的线性表。特殊在：

只能在固定的两端操作线性表

只要满足上述条件，那么这种特殊的线性表就会呈现出一种"先进先出"的逻辑，这种逻辑就被称为队列。

由于约定了只能在线性表固定的两端进行操作，于是给队列这种特殊的线性表的插入删除，起个特殊的名称：

队头：可以删除节点的一端

队尾：可以插入节点的一端

入队：将节点插入到队尾之后，函数名通常为enQueue()

出队：将队头节点从队列中剔除，函数名通常为outQueue()

取队头：取得队头元素，但不出队，函数名通常为front()

本题就是手撸数据结构中基本的队列结构，常用的有两种，一种是用链表实现，一种是数组实现。

1，数组实现

typedef struct {    int value[1000];    int len;} FrontMiddleBackQueue;  FrontMiddleBackQueue* frontMiddleBackQueueCreate() {    FrontMiddleBackQueue *queue = (FrontMiddleBackQueue *)malloc(sizeof(FrontMiddleBackQueue));    memset(queue,0,sizeof(FrontMiddleBackQueue));    return queue;} void insert(FrontMiddleBackQueue* obj, int pos, int val){    //在pos位置插入val，则pos(从0开始)位置后的数统一向后挪一个位置,队列长度加1    int i = 0;    for(i=obj->len; i>pos; i--)    {        obj->value[i] = obj->value[i-1];    }    obj->value[pos] = val;    obj->len++;} int pop(FrontMiddleBackQueue* obj, int pos){    //弹出pos位置的val,则pos(从0开始)位置后向前统一挪一个位置，队列长度减一    if(obj->len == 0)        return -1;    int i = 0;    int popval = obj->value[pos]; //先将pos位置的数保存下来，不然下面的移位操作就覆盖了pos位置的值    for(i=pos; ilen-1; i++)    {        obj->value[i] = obj->value[i+1];    }    obj->len--;    return popval;} void frontMiddleBackQueuePushFront(FrontMiddleBackQueue* obj, int val) {    insert(obj,0,val);} void frontMiddleBackQueuePushMiddle(FrontMiddleBackQueue* obj, int val) {    insert(obj,obj->len/2,val);} void frontMiddleBackQueuePushBack(FrontMiddleBackQueue* obj, int val) {    insert(obj,obj->len,val);} int frontMiddleBackQueuePopFront(FrontMiddleBackQueue* obj) {    return pop(obj,0);} int frontMiddleBackQueuePopMiddle(FrontMiddleBackQueue* obj) {    return pop(obj,(obj->len-1)/2);} int frontMiddleBackQueuePopBack(FrontMiddleBackQueue* obj) {    return pop(obj, obj->len-1);} void frontMiddleBackQueueFree(FrontMiddleBackQueue* obj) {    free(obj);} /** * Your FrontMiddleBackQueue struct will be instantiated and called as such: * FrontMiddleBackQueue* obj = frontMiddleBackQueueCreate(); * frontMiddleBackQueuePushFront(obj, val);  * frontMiddleBackQueuePushMiddle(obj, val);  * frontMiddleBackQueuePushBack(obj, val);  * int param_4 = frontMiddleBackQueuePopFront(obj);  * int param_5 = frontMiddleBackQueuePopMiddle(obj);  * int param_6 = frontMiddleBackQueuePopBack(obj);  * frontMiddleBackQueueFree(obj);*/

运行结果

2，链表实现

1，设计链表结构，链表维持一个头节点和尾结点，头节点始终在最前面并且头结点的data存储整个队列的节点数，尾结点始终是最后一个节点

2，设计插入节点函数和删除节点函数，push和pop操作只需要根据不同场景传入不同的参数即可完成统一的操作

typedef struct tag_Node {    int data;    struct tag_Node* next, *prev;}Node;  typedef struct {    Node* front;    Node* rear;} FrontMiddleBackQueue;  FrontMiddleBackQueue* frontMiddleBackQueueCreate() {    FrontMiddleBackQueue* que = (FrontMiddleBackQueue *)malloc(sizeof(FrontMiddleBackQueue));    que->front = (Node *)malloc(sizeof(Node));    que->rear = (Node *)malloc(sizeof(Node));    que->front->data = 0;    que->front->next = NULL;    que->rear->data = 0;    que->rear->next = NULL;    que->front->next = que->rear;    que->rear->prev = que->front;        return que;} void AddNode(FrontMiddleBackQueue* obj, Node *cur, int val) {    Node* addNode = (Node *)malloc(sizeof(Node));    addNode->data = val;    addNode->prev = cur->prev;    addNode->next = cur;        cur->prev->next = addNode;    cur->prev = addNode;        obj->front->data++;    return;} Node* GetMiddleNode(FrontMiddleBackQueue* obj, bool isAdd){    Node* tmp = obj->front->next;        int len = isAdd ? (obj->front->data / 2) : ((obj->front->data - 1) / 2);    for (int i = 0; i < len; i++) {        tmp = tmp->next;    }    return tmp;} void frontMiddleBackQueuePushFront(FrontMiddleBackQueue* obj, int val) {    AddNode(obj, obj->front->next, val);    return;} void frontMiddleBackQueuePushMiddle(FrontMiddleBackQueue* obj, int val) {    AddNode(obj, GetMiddleNode(obj, true), val);    return;} void frontMiddleBackQueuePushBack(FrontMiddleBackQueue* obj, int val) {    AddNode(obj, obj->rear, val);    return;} int RemoveNode(FrontMiddleBackQueue* obj, Node* cur){    if (obj->front->data == 0) {        return -1;    }    cur->next->prev = cur->prev;    cur->prev->next = cur->next;     obj->front->data--;    int item = cur->data;    free(cur);    return item;} int frontMiddleBackQueuePopFront(FrontMiddleBackQueue* obj) {    return RemoveNode(obj, obj->front->next);} int frontMiddleBackQueuePopMiddle(FrontMiddleBackQueue* obj) {    return RemoveNode(obj, GetMiddleNode(obj, false));} int frontMiddleBackQueuePopBack(FrontMiddleBackQueue* obj) {    return RemoveNode(obj, obj->rear->prev);} void frontMiddleBackQueueFree(FrontMiddleBackQueue* obj) {    while (RemoveNode(obj, obj->front->next) != -1);    free(obj->front);    free(obj->rear);    free(obj);    return;} /** * Your FrontMiddleBackQueue struct will be instantiated and called as such: * FrontMiddleBackQueue* obj = frontMiddleBackQueueCreate(); * frontMiddleBackQueuePushFront(obj, val);  * frontMiddleBackQueuePushMiddle(obj, val);  * frontMiddleBackQueuePushBack(obj, val);  * int param_4 = frontMiddleBackQueuePopFront(obj);  * int param_5 = frontMiddleBackQueuePopMiddle(obj);  * int param_6 = frontMiddleBackQueuePopBack(obj);  * frontMiddleBackQueueFree(obj);*/

运行结果：

感谢各位的阅读，以上就是"C语言如何设计前中后队列"的内容了，经过本文的学习后，相信大家对C语言如何设计前中后队列这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是，小编将为大家推送更多相关知识点的文章，欢迎关注！