연결리스트 큐(Queue) 구현

연결리스트 큐(Queue)

#include <stdio.h>
#include <stdlib.h>
#define ERROR_CODE 65000
typedef int element;

typedef struct node{
	element data;
	struct node* link;
}Node;

typedef struct{
	Node* front;
	Node* rear;
}LinkedQueue;

LinkedQueue* createQueue(){
	LinkedQueue *q=(LinkedQueue*)malloc(sizeof(LinkedQueue));
	q->front=NULL;
	q->rear=NULL;
	return q;
}

int isEmpty(LinkedQueue* q){
	if(q->front==NULL)return 1;
	else return 0;
}

int enQueue(LinkedQueue* q, element data){
	Node* newNode = (Node*)malloc(sizeof(Node));
	
	if(newNode == NULL){							//예외처리(노드를 위한 메모리 할당 실패)
		printf("Memory allocation error!\n");
		return 0;
	}

	newNode->data = data;
	newNode->link = NULL;
	
	if(isEmpty(q)){									//처음 삽입 할 때
		q->front = newNode;
		q->rear = newNode;
	}
	else{
		q->rear->link = newNode;
		q->rear = newNode;
	}
	return 1;
}

element deQueue(LinkedQueue* q){
	Node*temp;
	element data;
	if(isEmpty(q)){
		printf("Queue is Empty\n");
		return ERROR_CODE;
	}
	temp = q->front;
	data = temp->data;
	if(q->front == q->rear){					//노드가 하나 남은 경우
		q->front = q->rear = NULL;
	}
	else{
		q->front= q->front->link;
	}
	free(temp);
	return data;
}

element peek(LinkedQueue *q){
	if(isEmpty(q)){
		printf("Queue is Empty\n");
		return ERROR_CODE;
	}
	return q->front->data;
}

void printQueue(LinkedQueue *q){
	Node* temp = q->front;
	while(temp != NULL){
		printf("%d\t", temp->data);
		temp = temp->link;
	}
	printf("\n");
}

int main(){
	LinkedQueue *q1, *q2 ;
	q1 = createQueue();
	q2 = createQueue();
	enQueue(q1,10);
	printQueue(q1);
	enQueue(q1,20);
	printQueue(q1);
	enQueue(q1,30);
	printQueue(q1);
	deQueue(q1);
	printQueue(q1);
	deQueue(q1);
	printQueue(q1);
	deQueue(q1);
	printQueue(q1);
	return 0;
}