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MY_BOOK/ebook_src/abstract_structures/QueueClass.py

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+#!/usr/bin/env python
+# Time: 5 min
+
+__author__ = "bt3"
+
+
+class Queue(object):
+    def __init__(self):
+        self.enq = []
+        self.deq = []
+
+    def enqueue(self, item):
+        return self.enq.append(item)
+
+    def deque(self):
+        if not self.deq:
+            while self.enq:
+                self.deq.append(self.enq.pop())
+        return self.deq.pop()
+
+    def peak(self):
+        if not self.deq:
+            while self.enq:
+                self.deq.append(self.enq.pop())
+        if self.deq:
+            return self.deq[-1]
+
+    def size(self):
+        return len(self.enq) + len(self.deq)
+
+    def isempty(self):
+        return not (self.enq + self.deq)
+
+if __name__ == '__main__':
+    q = Queue()
+    for i in range(1,11):
+        q.enqueue(i)
+    print 'Size:',  q.size()
+    print 'Is empty?', q.isempty()
+    print 'Peak: ', q.peak()
+    print
+    print 'Dequeuing...'
+    for i in range(10):
+        print q.deque()
+    print 'Size:',  q.size()
+    print 'Is empty?', q.isempty()
+    print 'Peak: ', q.peak()