Added Queues

Author: pythonioncoder

Queue.py

@@ -0,0 +1,59 @@
+'''
+Overview:
+FIFO - First In First Out
+People in Queue = En Queue
+Remove People = De Queue
+
+Implementation:
+	Remove and Add on either end (First/Last)
+	List
+		One end is O(1) other is O(n) because of re-indexing
+	Linked List
+		Removing on one end is O(n) because of traversal,
+			but everything else is O(1)
+		Therefore, you want to only En-queue from Last
+			and de-queue from First
+'''
+
+
+class Node:
+	def __init__(self, value):
+		self.value = value
+		self.next = None
+
+
+class Queue:
+	def __init__(self, value):
+		new_node = Node(value)
+		self.first = new_node
+		self.last = new_node
+		self.length = 1
+
+	def print_queue(self):
+		temp = self.first
+		while temp is not None:
+			print(temp.value)
+			temp = temp.next
+
+	def enqueue(self, value):
+		new_node = Node(value)
+		if self.first is None:
+			self.first = new_node
+			self.last = new_node
+		else:
+			self.last.next = new_node
+			self.last = new_node
+		self.length += 1
+
+	def dequeue(self):
+		if self.first is None:
+			return None
+		temp = self.first
+		if self.length == 1:
+			self.first = None
+			self.last = None
+		else:
+			self.first = temp.next
+			temp.next = None
+		self.length -= 1
+		return temp