Animal Shelter

Author: anantkaushik

stacks-and-queues/animal-shelter.py

@@ -0,0 +1,69 @@
+"""
+An animal shelter, which holds only dogs and cats, operates on a strictly "first in, first out" basis. People must adopt
+either the "oldest" (based on arrival time) of all animals at the shelter, or they can select whether they would prefer a
+dog or a cat (receive the oldest animal of that type). They cannot select which specific animal they would like.
+Create the data structures to maintain this system and implement operations such as enqueue, dequeueAny, dequeueDog, and 
+dequeueCat. You may use the built-in LinkedList data structure.
+"""
+class Animal:
+	def __init__(self, animalName=None, animalType=None):
+		self.animalName = animalName
+		self.animalType = animalType
+		self.next = None
+		self.timestamp = 0
+		
+class AnimalShelter:
+	def __init__(self):
+		self.headCat = None
+		self.tailCat = None
+		self.headDog = None
+		self.tailDog = None
+		self.order = 0
+
+	def enqueue(self, animalName, animalType):
+		self.order += 1 
+		newAnimal = Animal(animalName, animalType)
+		newAnimal.timestamp = self.order
+
+		if animalType == 'cat':
+			if not self.headCat:
+				self.headCat = newAnimal
+			if self.tailCat:
+				self.tailCat.next = newAnimal
+			self.tailCat = newAnimal
+
+		elif animalType == 'dog':
+			if not self.headDog:
+				self.headDog = newAnimal
+			if self.tailDog:
+				self.tailDog.next = newAnimal
+			self.tailDog = newAnimal
+
+	def dequeueCat(self):
+		if self.headCat:
+			newAnimal = self.headCat
+			self.headCat = newAnimal.next
+			return str(newAnimal.animalName)
+		else:
+			return "No cat left!"
+
+	def dequeueDog(self):
+		if self.headDog:
+			newAnimal = self.headDog
+			self.headDog = newAnimal.next
+			return str(newAnimal.animalName)
+		else:
+			return "No dog left!"
+			
+	def dequeueAny(self):
+		if self.headCat and not self.headDog:
+			return self.dequeueCat()
+		elif not self.headCat and self.headDog:
+			return self.dequeueDog()
+		elif self.headCat:
+			if self.headCat.timestamp < self.headDog.timestamp:
+				return self.dequeueCat()
+			else:
+				return self.dequeueDog()
+		else:
+			return "No animal left!"