자료구조 큐

queue.c

#include <stdio.h>

#define SIZE 5 /* 큐의 크기 */

int menu(void);
void view_queue(), insert_menu(), delete_menu();
int insertQ(char obj);
char deleteQ();
int isempty();
int isfull();

char queue[SIZE]; // 배열로 만든 큐
int rear = -1;
int front = -1;

void main(){
	int choice;
	do{
		choice = menu();
		switch(choice){
			case 1: insert_menu();
				break;
			case 2: delete_menu();
				break;
		}
	}while(choice!=3);
}

int menu(){
	int i;
	printf("Basic Queue Program 1.0:\n");
	printf("1. Insert\n");
	printf("2. Delete\n");
	printf("3. Quit\n");
	
	do{
		printf("Choose your selection: ");
		scanf("%d",&i);
	}while(i<1 || i>3);
	
	return i;
}

// 전체 큐 보기
void view_queue(){
	int i;
	printf("+0+1+2+3+4+\n");
	printf("+-+-+-+-+-+\n");
	for(i=0; i<=front; i++)
		printf("| ");
	for(i=front+1; i<=rear; i++)
		printf("|%c",queue[i]);
	printf("\n");
	printf("+-+-+-+-+-+\n");
	printf("front = %d, rear = %d\n\n", front, rear);
}

// 큐에 객체를 삽입하는 메뉴
void insert_menu(){
	char obj;
	printf("Insert New Object : ");
	getchar();
	scanf("%c",&obj);
	if(insertQ(obj)) view_queue();
}

int insertQ(char obj){
	int i;
	
	if(isfull()){
		printf("Queue is full\n");
		return 0;
	}
	
	if(rear == SIZE-1){
		for(i=front+1; i<SIZE; i++)
			queue[i-front-1] = queue[i];
		rear-=front+1;
		front = -1;
	}
	queue[++rear] = obj;
	return 1;
}

int isfull(){
	if(rear==SIZE-1 && front==-1) return 1;
	return 0;
}

void delete_menu(){
	char obj;
	if(obj=deleteQ()) view_queue();
}

char deleteQ(){
	char ch;
	if(isempty()){
		printf("Queue is empty!!\n");
		return 0;
	}
	
	ch = queue[++front];
	if(front==rear) front = rear = -1;
	
	return ch;
}

int isempty(){
	if(front == rear) return 1;
	return 0;
}