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Copy pathMain_10845.java
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66 lines (60 loc) · 1.52 KB
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package baekjoon.queue;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.LinkedList;
import java.util.Objects;
/*
* sout은 느리다
* */
public class Main_10845 {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
int n = Integer.parseInt(br.readLine());
LinkedList<Integer> queue = new LinkedList<>();
for (int i = 0; i < n; i++) {
String[] str = br.readLine().split(" ");
switch (str[0]) {
case "push":
queue.add(Integer.parseInt(str[1]));
break;
case "pop":
Integer popNumber = queue.poll();
if (Objects.isNull(popNumber)) {
bw.write("-1\n");
} else {
bw.write(popNumber + "\n");
}
break;
case "size":
bw.write(queue.size() + "\n");
break;
case "empty":
int isEmpty = queue.isEmpty() ? 1 : 0;
bw.write(isEmpty + "\n");
break;
case "front":
Integer frontNumber = queue.peekFirst();
if (Objects.isNull(frontNumber)) {
bw.write("-1\n");
} else {
bw.write(frontNumber + "\n");
}
break;
case "back":
Integer backNumber = queue.peekLast();
if (Objects.isNull(backNumber)) {
bw.write("-1\n");
} else {
bw.write(backNumber + "\n");
}
break;
}
}
bw.flush();
bw.close();
}
}