Three Hundred - Forty-Eight Commit: Implement LinkedListQueue Class

Author: AAdewunmi

Section_12(Graphs)/queuelinkedlist.py

@@ -0,0 +1,54 @@
+# Node Class
+class _Node:
+    __slots__ = '_element', '_next'
+
+    def __init__(self, element, next):
+        self._element = element
+        self._next = next
+
+# LinkedListQueue Class
+
+class LinkedListQueue:
+    def __init__(self):
+        self._front = None
+        self._rear = None
+        self._size = 0
+
+    def __len__(self):
+        return self._size
+
+    def is_empty(self):
+        return self._size == 0
+
+    def enqueue(self, element):
+        newest = _Node(element, None)
+        if self.is_empty():
+            self._front = newest
+        else:
+            self._rear._next = newest
+        self._rear = newest
+        self._size += 1
+
+    def dequeue(self):
+        if self.is_empty():
+            print('Queue is Empty')
+            return
+        e = self._front._element
+        self._front = self._front._next
+        self._size -= 1
+        if self.is_empty():
+            self._rear = None
+        return e
+
+    def peek(self):
+        if self.is_empty():
+            print('Queue is Empty')
+            return
+        return self._front._element
+
+    def display(self):
+        p = self._front
+        while p:
+            print(p._element, end=' <-- ')
+            p = p._next
+        print()