[백준 10854] 큐 (JAVA) - Queue

[문제링크]

https://www.acmicpc.net/problem/10845

 

[풀이소스]

package algorithm;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.StringTokenizer;
 
public class Queue10845 {
    public static LinkedList<Integer> queue;
    
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int testcase=Integer.parseInt(br.readLine());
        
        StringTokenizer st=null;
        queue=new LinkedList<Integer>();
        StringBuilder result=new StringBuilder();
        int lastIn=-1;
 
        while(testcase-->0) {
            st=new StringTokenizer(br.readLine());
            String method=st.nextToken();
            
            if (method.equals("push")) {
                lastIn=Integer.parseInt(st.nextToken());
                queue.offer(lastIn);
            } else if (method.equals("pop")) {
                if (queue.isEmpty()) {
                    result.append("-1 \n");
                    lastIn=-1;
                }
                else {
                    result.append(queue.poll()+"\n");
                    if(queue.size()==0) lastIn=-1;
                }
            } else if(method.equals("size")) {
                result.append(queue.size()+"\n");
            } else if(method.equals("empty")) {
                if(queue.isEmpty()) {
                    result.append("1 \n");
                } else {
                    result.append("0 \n");
                }
            } else if(method.equals("front")) {
                if (queue.isEmpty()) result.append("-1 \n");
                else result.append(queue.peek()+"\n");
            } else if(method.equals("back")) {
                if (queue.isEmpty()) result.append("-1 \n");
                else result.append(lastIn+" \n");
            }
        }
        System.out.println(result);
    }
 
}
 

 

 

[느낀점]

  - Queue는 LinkedList활용!

  - 가장 많이 활용하는 변수는 밖에

  - 활용될 변수는 조건문안이 아닌 실행될 곳에!

  - 너무 뺑끌뺑글~~~ 돌려생각하지말기!