Data-Structures-and-Algorithms-in-Python/Queue.py at master · abhi227070/Data-Structures-and-Algorithms-in-Python · 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
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
class Node:

    def __init__(self, value):
        self.data = value
        self.next = None

class Queue:

    def __init__(self):
        self.front = None
        self.rear = None
        self.n = 0

    def enqueue(self, value):

        new_node = Node(value)

        if self.rear == None:

            self.rear = new_node
            self.front = self.rear
            self.n += 1

        else:

            self.rear.next = new_node
            self.rear = new_node
            self.n += 1

    def dequeue(self):

        if self.front == None:
            print("Queue is empty")
            return

        else:
            self.front = self.front.next
            self.n -=1

    def __str__(self):

        curr = self.front
        result = ''

        while curr != None:
            result = result + str(curr.data) + ' '
            curr = curr.next


        return result[:-1]

    def __len__(self):
        return self.n

    def isempty(self):
        return self.front == None

    def front_value(self):
        if self.front == None:
            print("Queue is empty")
            return

        else:
            return self.front.data

    def rear_value(self):
        if self.rear == None:
            print("Queue is empty")
            return

        else:
            return self.rear.data

if __name__ == "__main__":

    q = Queue()

    q.enqueue(1)
    q.enqueue(2)
    q.enqueue(3)
    q.enqueue(4)

    print(len(q))
    print(q.isempty())
    print(q.front_value())
    print(q.rear_value())
    print(q)