复习一下队列与循环队列的实现（C语言）
1、单链队列：
1 typedef struct QNode{ //若不写typedef，在C中每次定义QNode需要在前面加上struct，而C++不必 2 QElemType data; 3 struct QNode *next; 4 }QNode,*QueuePtr; 5 6 typedef struct{ //若不写结构体名，则需要加上typedef 7 QueuePtr front; 8 QueuePtr rear; 9 }LinkQueue; 10 11 status InitQueue(LinkQueue &Q){ //初始化 12 Q.front = Q.rear = (QueuePtr) malloc(sizeof(QNode)); 13 if(!Q.front) 14 exit(OVERFLOW); 15 Q.front -> next = NULL; 16 return OK; 17 } 18 19 status EnQueue(LinkQueue &Q,QElemType &e){ //把元素e入队 20 p = (QueuePtr) malloc(sizeof(QNode)); 21 if(!p) 22 exit(OVERFLOW); 23 p -> next = NULL; 24 p -> data = e; 25 Q.rear -> next = p; 26 Q.rear = p; 27 return OK; 28 } 29 30 status Dequeue(LinkQueue &Q,QElemType &e){ //删除对头元素，且把队顶元素保存在e中 31 if(Q.front == Q.rear) 32 return ERROR; 33 p = Q.front -> next; 34 e = p -> data; 35 Q.front -> next = p -> next; 36 if(Q.rear == p) 37 Q.rear = Q.front; 38 free(p); 39 return OK; 40 }
2、循环队列
1 #define MAXQSIZE 100 2 3 typedef struct{ 4 QElemType *base; 5 int front; 6 int rear; 7 }SqQueue; 8 9 status InitQueue(SqQueue &Q){ 10 Q.base = (QElemType *) malloc(MAXQSIZE*sizeof(QElemType)); 11 if(!Q.base) 12 exit(OVERFLOW); 13 Q.front = Q.rear = 0; 14 return OK; 15 } 16 17 status EnQueue(SqQueue &Q,QElemType &e){ 18 if((Q.rear+1)%MAXQSIZE == Q.front) //队列已满 19 return ERROR; 20 Q.base[Q.rear] = e; 21 Q.rear = (Q.rear+1)%MAXQSIZE; 22 return OK; 23 } 24 25 status Dequeue(SqQueue &Q,QElemType &e){ 26 if(Q.front == Q.rear) 27 return ERROR; 28 e = Q.base[Q.front]; 29 Q.front = (Q.front+1)%MAXQSIZE; 30 return OK; 31 }