#include 
     
      #include 
      
       #define ERROR 1e5typedef struct Node {    int Element;    struct Node *next, *last;}*PtrToNode;typedef struct DequeRecord {    struct Node *front, *rear;}*Deque;typedef enum { push, pop, inject, eject, disp, end } Operation; Deque CreateDeque(){    Deque deque = (Deque)malloc(sizeof(struct DequeRecord));    PtrToNode temp = (PtrToNode)malloc(sizeof(struct Node));    temp->last = NULL;    temp->next = NULL;    deque->front = temp;    deque->rear = temp;    return deque; } int Push(int X, Deque D){    PtrToNode temp;    temp = (PtrToNode)malloc(sizeof(struct Node));    if (!temp)        return 0;    temp->Element = X;    // 空队列情况    if (D->front == D->rear){        D->front->next = temp;        temp->last = D->front;        temp->next = NULL;        D->rear = temp;        return 1;    }    // 一般情况    temp->next = D->front->next;    temp->last = D->front;    D->front->next->last = temp;    D->front->next = temp;    return 1;} int Pop(Deque D){    PtrToNode temp;    int X;    // 空队列    if (D->front == D->rear)        return ERROR;     temp = D->front->next;    X = temp->Element;    // 如果只有一个节点的情况    if (D->front->next == D->rear){        D->rear = D->front;        D->rear->next = NULL;        free(temp);        return X;    }    // 一般情况    temp->next->last = D->front;    D->front->next = temp->next;    free(temp);    return X;} // 末尾添加一个元素int Inject(int X, Deque D){    PtrToNode temp;    temp = (PtrToNode)malloc(sizeof(struct Node));    if (!temp)        return 0;    temp->Element = X;    // 空队列    if (D->front == D->rear){        D->front->next = temp;        temp->last = D->front;        D->rear = temp;        return 1;    }    D->rear->next = temp;    temp->next = NULL;    temp->last = D->rear;    D->rear = temp;    return 1;} // 从末尾移除一个元素int Eject(Deque D){    PtrToNode temp;    int X;    if (D->front == D->rear)        return ERROR;     temp = D->rear;    X = temp->Element;    D->rear = temp->last;    D->rear->next = NULL;    free(temp);    return X;}Operation GetOp(){    int op;    puts("请输入操作码：1 左入队，2 左出队，3 右入队，4 右出队，5 显示队列，6 退出");    scanf("%d",&op);    switch(op){        case 1:return push;        case 2:return pop;        case 3:return inject;        case 4:return eject;        case 5:return disp;        case 6:return end;        default:exit(1);    }}// 左边front，右边rear，next指向右,带头节点void PrintDeque(Deque D){    PtrToNode p1;    p1=D->front->next;          // 头节点，front所指单元的next域    printf("队列中剩余元素：");    while(p1!=D->rear->next){        printf("%d ",p1->Element);        p1=p1->next;    }    printf("\n");}     // 该双端队列可在两端进行入队和出队操作，在左边进行操作的时候要考虑头节点int main(){    int e;    Deque D;    int done = 0;     D = CreateDeque();    while (!done) {        switch(GetOp()) {        case push:            puts("push:");            scanf("%d", &e);            if (!Push(e, D)) printf("Memory is Full!\n");            break;        case pop:            e = Pop(D);            if ( e==ERROR ) printf("Deque is Empty!\n");            break;        case inject:             puts("inject:");            scanf("%d", &e);            if (!Inject(e, D)) printf("Memory is Full!\n");            break;        case eject:            e = Eject(D);            if ( e==ERROR ) printf("Deque is Empty!\n");            break;        case disp:            PrintDeque(D);            break;        case end:            done = 1;            break;        }    }    return 0;}