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Copy pathBOJ_18258.java
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61 lines (55 loc) · 1.83 KB
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package baekjoon.silver;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;
public class BOJ_18258 {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringBuilder sb = new StringBuilder();
StringTokenizer st;
int N = Integer.parseInt(br.readLine());
Queue q = new LinkedList();
int lastValue = 0;
for (int i = 0; i < N; i++) {
st = new StringTokenizer(br.readLine());
String operator = st.nextToken();
if(operator.equals("push")) { // push
int value = Integer.parseInt(st.nextToken());
q.offer(value);
lastValue = value;
}
else if(operator.equals("pop")) {
if(q.isEmpty())
sb.append("-1\n");
else {
sb.append(q.poll() + "\n");
}
}
else if(operator.equals("size")) {
sb.append(q.size() + "\n");
}
else if(operator.equals("empty")) {
if(q.isEmpty())
sb.append("1\n");
else
sb.append("0\n");
}
else if(operator.equals("front")) {
if(q.isEmpty())
sb.append("-1\n");
else
sb.append(q.peek() + "\n");
}
else if(operator.equals("back")) {
if(q.isEmpty())
sb.append("-1\n");
else
sb.append(lastValue + "\n");
}
}
System.out.println(sb);
}
}