Learning-Data-Structures-and-Algorithm-Python/implement_queue_linkedList.py at master · AnushreeBagchi/Learning-Data-Structures-and-Algorithm-Python · GitHub

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

class Queue:
    def __init__(self):
        self.head = None
        self.tail = None
        self.queue_size = 0

    def size(self):
        return self.queue_size
    def is_empty(self):
        return self.queue_size == 0
    def enqueue(self, value):
        if self.head is None:
            self.head = Node(value)
            self.tail = self.head
        else:
            self.tail.next = Node(value)
            self.tail = self.tail.next
        self.queue_size += 1
    def dequeue(self):
        if self.head is None:
            return None
        value = self.head.value
        self.head = self.head.next
        self.queue_size -=1
        return value
    def top(self):
        return self.head.value

q = Queue()
q.enqueue(1)
q.enqueue(2)
q.enqueue(3)

# Test size
print ("Pass" if (q.size() == 3) else "Fail")

# Test dequeue
print ("Pass" if (q.dequeue() == 1) else "Fail")

# Test enqueue
q.enqueue(4)
print ("Pass" if (q.dequeue() == 2) else "Fail")
print ("Pass" if (q.dequeue() == 3) else "Fail")
print ("Pass" if (q.dequeue() == 4) else "Fail")
q.enqueue(5)
print ("Pass" if (q.size() == 1) else "Fail")