-
Notifications
You must be signed in to change notification settings - Fork 18
/
QueueImplementUsingTwoStacks.java
146 lines (141 loc) · 4.71 KB
/
QueueImplementUsingTwoStacks.java
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
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/*
* Java Program to Implement Queue using Two Stacks
*/
import java.util.*;
/* Class queueUsingStack */
class queueUsingStack
{
Stack<Integer> s ;
Stack<Integer> tmp ;
/* Constructor */
public queueUsingStack()
{
s = new Stack<Integer>();
tmp = new Stack<Integer>();
}
/* Function to insert an element to the queue */
public void insert(int data)
{
/* if no element is present in stack s then
* push the new element to stack s */
if (s.size() == 0)
s.push(data);
else
{
/* if elements are present in stack s then
* pop all the elements from stack s and
* push them to stack tmp */
int l = s.size();
for (int i = 0; i < l; i++)
tmp.push(s.pop());
/* push the new element to stack s */
s.push(data);
/* pop all elements from stack tmp and
* push them to stack s */
for (int i = 0; i < l; i++)
s.push(tmp.pop());
}
}
/* Function to remove front element from the queue */
public int remove()
{
if (s.size() == 0)
throw new NoSuchElementException("Underflow Exception");
return s.pop();
}
/* Function to check the front element of the queue */
public int peek()
{
if (s.size() == 0)
throw new NoSuchElementException("Underflow Exception");
return s.peek();
}
/* Function to check if queue is empty */
public boolean isEmpty()
{
return s.size() == 0 ;
}
/* Function to get the size of the queue */
public int getSize()
{
return s.size();
}
/* Function to display the status of the queue */
public void display()
{
System.out.print("\nQueue = ");
int l = getSize();
if (l == 0)
System.out.print("Empty\n");
else
{
/* Iterator wont return for stack in order */
for (int i = l - 1; i >= 0; i--)
System.out.print(s.get(i)+" ");
System.out.println();
}
}
}
/* Class QueueImplementUsingTwoStacks */
public class QueueImplementUsingTwoStacks
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
/* Creating object of class queueUsingStack */
queueUsingStack qus = new queueUsingStack();
/* Perform Queue Operations */
System.out.println("Queue Using Two Stacks Test\n");
char ch;
do
{
System.out.println("\nQueue Operations");
System.out.println("1. insert");
System.out.println("2. remove");
System.out.println("3. peek");
System.out.println("4. check empty");
System.out.println("5. size");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println("Enter integer element to insert");
qus.insert( scan.nextInt() );
break;
case 2 :
try
{
System.out.println("Removed Element = "+ qus.remove() );
}
catch (Exception e)
{
System.out.println("Error : " + e.getMessage());
}
break;
case 3 :
try
{
System.out.println("Peek Element = "+ qus.peek() );
}
catch (Exception e)
{
System.out.println("Error : " + e.getMessage());
}
break;
case 4 :
System.out.println("Empty status = "+ qus.isEmpty() );
break;
case 5 :
System.out.println("Size = "+ qus.getSize() );
break;
default :
System.out.println("Wrong Entry \n ");
break;
}
/* Display Queue */
qus.display();
System.out.println("\nDo you want to continue (Type y or n) \n");
ch = scan.next().charAt(0);
} while (ch == 'Y'|| ch == 'y');
}
}