Java 10845 큐

 

 

풀이 :

int형 배열로 큐의 기능을 하는 CustomQueue 클래스를 구현하여 해당 문제를 풀이하였습니다.

 

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    static class CustomQueue {
        int[] queue;
        int begin;
        int end;

        public CustomQueue(int n){
            this.queue = new int[n];
            this.begin = 0;
            this.end = 0;
        }

        public void push(int n){
            end++;
            queue[end-1] = n;
        }

        public int pop(){
            if((end - begin) == 0){
                return -1;
            }
            int i = queue[begin];
            begin++;
            return i;
        }

        public int size(){
            return end - begin;
        }

        public int empty(){
            if((end - begin) == 0){
                return 1;
            }
            return 0;
        }

        public int front(){
            if((end - begin) == 0)
                return -1;
            return queue[begin];
        }

        public int back(){
            if((end - begin) == 0)
                return -1;
            return queue[end-1];
        }
    }

    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        StringTokenizer st;
        CustomQueue queue = new CustomQueue(n);
        StringBuilder sb = new StringBuilder();

        for(int i = 0; i < n; i++){
            st = new StringTokenizer(br.readLine());
            String str = st.nextToken();
            switch (str){
                case "push":
                    int data = Integer.parseInt(st.nextToken());
                    queue.push(data);
                    break;
                case "pop":
                    int pop = queue.pop();
                    sb.append(pop).append("\n");
                    break;
                case "size":
                    int size = queue.size();
                    sb.append(size).append("\n");
                    break;
                case "empty":
                    int empty = queue.empty();
                    sb.append(empty).append("\n");
                    break;
                case "front":
                    int front = queue.front();
                    sb.append(front).append("\n");
                    break;
                case "back":
                    int back = queue.back();
                    sb.append(back).append("\n");
                    break;
                default:
                    break;
            }
        }
        System.out.print(sb);
    }
}