Implemented two-way linked list, queue and stack data structures

Author: KyattPL

data-structures/OneWayLinkedList.py

@@ -1,3 +1,4 @@
+# With Head only
 class OneWayLinkedList:
     class Element:
         def __init__(self, value):
@@ -50,7 +51,7 @@ def length(self):
         return count
 
     def remove(self, index):
-        if index < 0 or index > self.length():
+        if index < 0 or index >= self.length():
             return None
         elem = self.head
         temp = 0
@@ -73,7 +74,7 @@ def remove(self, index):
             return temp
 
     def add(self, val, index):
-        if index < 0 or self.length() < index:
+        if index < 0 or self.length() <= index:
             return False
         elif index == 0:
             elem = self.head

data-structures/Queue.py

@@ -0,0 +1,32 @@
+# Since Python doesn't have a built-in array data structure
+# I'm going to use a regural list with capacity (to make it interesting)
+class Queue:
+    def __init__(self, capacity=10):
+        self.list = []
+        self.capacity = capacity
+
+    def enqueue(self, value):
+        if len(self.list) != self.capacity:
+            self.list.append(value)
+            return True
+        else:
+            return "QueueOverflowException"
+
+    def dequeue(self):
+        if len(self.list) != 0:
+            val = self.list.pop(0)
+            return val
+        else:
+            return "IndexOutOfBoundsException"
+
+
+if __name__ == "__main__":
+    x = Queue(3)
+    print(x.enqueue(10))
+    print(x.enqueue(69))
+    print(x.enqueue(2137))
+    print(x.enqueue(423))
+    print(x.dequeue())
+    print(x.dequeue())
+    print(x.dequeue())
+    print(x.dequeue())

data-structures/Stack.py

@@ -0,0 +1,32 @@
+# Since Python doesn't have a built-in array data structure
+# I'm going to use a regural list with capacity (to make it interesting)
+class Stack:
+    def __init__(self, capacity=10):
+        self.list = []
+        self.capacity = capacity
+
+    def push(self, val):
+        if len(self.list) != self.capacity:
+            self.list.append(val)
+            return True
+        else:
+            return "StackOverflowException"
+
+    def pop(self):
+        if len(self.list) != 0:
+            val = self.list.pop()
+            return val
+        else:
+            return "IndexOutOfBoundsException"
+
+
+if __name__ == "__main__":
+    x = Stack(3)
+    print(x.push(10))
+    print(x.push(69))
+    print(x.push(2137))
+    print(x.push(423))
+    print(x.pop())
+    print(x.pop())
+    print(x.pop())
+    print(x.pop())

data-structures/TwoWayLinkedList.py

@@ -0,0 +1,145 @@
+# With Head and Tail
+class TwoWayLinkedList:
+    class Element:
+        def __init__(self, val):
+            self.value = val
+            self.next = None
+            self.previous = None
+
+    def __init__(self):
+        self.head = None
+        self.tail = None
+
+    def push(self, val):
+        if self.head is None:
+            newElem = self.Element(val)
+            self.head = newElem
+            self.tail = newElem
+        else:
+            newElem = self.Element(val)
+            self.tail.next = newElem
+            newElem.previous = self.tail
+            self.tail = newElem
+
+    def print_list(self):
+        elem = self.head
+        if elem is None:
+            return
+        else:
+            while elem != self.tail:
+                print(elem.value)
+                elem = elem.next
+            print(self.tail.value)
+
+    def print_reverse(self):
+        elem = self.tail
+        if elem is None:
+            return
+        else:
+            while elem != self.head:
+                print(elem.value)
+                elem = elem.previous
+            print(self.head.value)
+
+    def pop(self):
+        elem = self.tail
+        if elem is None:
+            return None
+        else:
+            newTail = elem.previous
+            val = elem.value
+            self.tail = newTail
+            return val
+
+    def contains(self, val):
+        elem = self.head
+        if elem is None:
+            return False
+        else:
+            while elem:
+                if elem.value == val:
+                    return True
+                else:
+                    elem = elem.next
+            return False
+
+    def length(self):
+        count = 0
+        elem = self.head
+        if elem is None:
+            return 0
+        else:
+            while elem:
+                count += 1
+                elem = elem.next
+            return count
+
+    def add(self, val, index):
+        if index < 0 or index >= self.length():
+            return None
+        else:
+            if index == 0:
+                elem = self.head
+                newElem = self.Element(val)
+                newElem.next = elem
+                elem.previous = newElem
+                self.head = newElem
+                return
+            else:
+                elem = self.head
+                ind = 1
+                while ind != index:
+                    ind += 1
+                    elem = elem.next
+                newElem = self.Element(val)
+                if elem.next:
+                    newElem.next = elem.next
+                    newElem.previous = elem
+                    elem.next.previous = newElem
+                    elem.next = newElem
+                else:
+                    newElem.next = None
+                    newElem.previous = elem
+                    elem.next = newElem
+
+    def remove(self, index):
+        if index < 0 or index >= self.length():
+            return None
+        else:
+            if index == 0:
+                elem = self.head
+                val = elem.value
+                self.head = elem.next
+                if self.head is None:
+                    self.tail = None
+                return val
+            else:
+                elem = self.head
+                ind = 0
+                while ind != index:
+                    ind += 1
+                    elem = elem.next
+                if self.tail != elem:
+                    val = elem.value
+                    elem.previous.next = elem.next
+                    elem.next.previous = elem.previous
+                    return val
+                else:
+                    val = elem.value
+                    elem.previous.next = None
+                    self.tail = elem.previous
+                    return val
+
+
+if __name__ == "__main__":
+    x = TwoWayLinkedList()
+    x.push(3)
+    x.push(69)
+    x.push(2137)
+    print(x.contains(69))
+    print(x.length())
+    x.print_list()
+    x.add(32, 1)
+    x.print_list()
+    x.remove(3)
+    x.print_list()