4-16 双端队列 （25分）

#include <stdio.h>
#include <stdlib.h>
#include<string.h>
#define ERROR -1
typedef int ElementType;
#define false 0
#define true 1
typedef enum { push, pop, inject, eject, end } Operation;
//typedef enum { false, true } bool;
typedef int Position;
typedef struct QNode *PtrToQNode;
struct QNode {
    ElementType *Data;      
    Position Front, Rear;   
    int MaxSize;            
};
typedef PtrToQNode Deque; 
Deque CreateDeque( int MaxSize )
{  
    Deque D = (Deque)malloc(sizeof(struct QNode));
    MaxSize++;
    D->Data = (ElementType *)malloc(MaxSize * sizeof(ElementType));
    D->Front = D->Rear = 0;
    D->MaxSize = MaxSize;
    return D;
}
bool Push( ElementType X, Deque D );
ElementType Pop( Deque D );
bool Inject( ElementType X, Deque D );
ElementType Eject( Deque D );
Operation GetOp();          
void PrintDeque( Deque D ); 
int main()
{
    ElementType X;
    Deque D;
    int N, done = 0;
    scanf("%d", &N);
    D = CreateDeque(N);
    while (!done) {
        switch(GetOp()) 
        {
        case push: 
            scanf("%d", &X);
            if (!Push(X, D)) printf("Deque is Full!\n");
            break;
        case pop:
            X = Pop(D);
            if ( X==ERROR ) printf("Deque is Empty!\n");
            else printf("%d is out\n", X);
            break;
        case inject: 
            scanf("%d", &X);
            if (!Inject(X, D)) printf("Deque is Full!\n");
            break;
        case eject:
            X = Eject(D);
            if ( X==ERROR ) printf("Deque is Empty!\n");
            else printf("%d is out\n", X);
            break;
        case end:
            PrintDeque(D);
            done = 1;
            break;
        }
    }
    return 0;
}
bool Push( ElementType X, Deque D )
{
    if( (D->Rear+1)%(D->MaxSize)==D->Front)
    {
        return false;
    }
    D->Front = (((D->Front )- 1) + D->MaxSize) % D->MaxSize;
    D->Data[D->Front]=X;
    return true;
}
ElementType Pop( Deque D )
{
    ElementType X;
    if((D->Rear==D->Front))
        return ERROR;
    X=D->Data[D->Front];
    D->Front=((D->Front)+1)%(D->MaxSize);
    return X;
}
bool Inject( ElementType X, Deque D )
{
    if( ((D->Rear)+1)%(D->MaxSize)==D->Front )
    {
        return false;
    }
    D->Data[D->Rear]=X;
    D->Rear=((D->Rear)+1)%(D->MaxSize);
    return true;
}
ElementType Eject( Deque D )
{
    ElementType X;
    if ( (D->Rear) == (D->Front) )
    {
        return ERROR;
    }
    D->Rear=(((D->Rear)-1)+(D->MaxSize))%(D->MaxSize);
    X=D->Data[D->Rear];
    return X;
}
Operation GetOp()
{
    char opt[7];
    scanf("%s", opt);
    if (strcmp(opt, "Push") == 0)
    {
        return push;
    }
    else 
        if (strcmp(opt, "Pop") == 0)
        {
            return pop;
        }
        else 
            if (strcmp(opt, "Inject") == 0)
            {
                return inject;
            }
            else 
                if (strcmp(opt, "Eject") == 0)
                {
                    return eject;
                }
                else 
                    if (strcmp(opt, "End") == 0)
                    {
                        return end;
                    }
}
void PrintDeque(Deque D)
{
    printf( "Inside Deque:" );
    while (D->Front!=D->Rear )
    {
        printf(" %d",D->Data[D->Front]);
        D->Front=((D->Front)+1)%(D->MaxSize);
    }
}