Algorithm_Practice/10845.java at master · ktyu/Algorithm_Practice · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
importjava.util.*;

publicclassMain {

publicstaticvoidmain(String[] args) {

Scannersc = newScanner(System.in);
intnum = sc.nextInt();
sc.nextLine();

Queue<Integer> q = newLinkedList<>();

for(inti=0; i<num; i++) {
Stringinstruction = sc.nextLine();

String[] s = instruction.split(" ");

if(s[0].equals("push")) {
q.add(Integer.valueOf(s[1]));
 }

elseif(s[0].equals("pop")) {
if(q.isEmpty())
System.out.println(-1);
else
System.out.println(q.remove());
 }

elseif(s[0].equals("size")) {
System.out.println(q.size());
 }

elseif(s[0].equals("empty")) {
if(q.isEmpty())
System.out.println(1);
else
System.out.println(0);
 }

elseif(s[0].equals("front")) {
if(q.isEmpty())
System.out.println(-1);
else
System.out.println(q.peek());
 }

elseif(s[0].equals("back")) {
if(q.isEmpty())
System.out.println(-1);
else
System.out.println(((LinkedList<Integer>) q).peekLast());
 }
 }
 }
}