Added queue on stack

Author: ShyamW

data_structures/QueueOnList.py data_structures/Queue/QueueOnList.pydata_structures/QueueOnList.py renamed to data_structures/Queue/QueueOnList.py

@@ -0,0 +1,51 @@
+"""Queue represented by a pseudo stack (represented by a list with pop and append)"""
+classQueue():
+def__init__(self):
+self.stack= []
+self.length=0
+
+def__str__(self):
+printed='<'+str(self.stack)[1:-1] +'>'
+returnprinted
+
+"""Enqueues{@code item}
+ @param item
+ item to enqueue"""
+defput(self, item):
+self.stack.append(item)
+self.length=self.length+1
+
+
+"""Dequeues{@code item}
+ @requirement: |self.length| > 0
+ @return dequeued
+ item that was dequeued"""
+defget(self):
+self.rotate(1)
+dequeued=self.stack[self.length-1]
+self.stack=self.stack[:-1]
+self.rotate(self.length-1)
+self.length=self.length-1
+returndequeued
+
+"""Rotates the queue{@code rotation} times
+ @param rotation
+ number of times to rotate queue"""
+defrotate(self, rotation):
+foriinrange(rotation):
+temp=self.stack[0]
+self.stack=self.stack[1:]
+self.put(temp)
+self.length=self.length-1
+
+"""Reports item at the front of self
+ @return item at front of self.stack"""
+deffront(self):
+front=self.get()
+self.put(front)
+self.rotate(self.length-1)
+returnfront
+
+"""Returns the length of this.stack"""
+defsize(self):
+returnself.length