Python Programs

Author: OmkarPathak

Programs/P31_SinglyLinkedList.py

@@ -1,100 +1,94 @@
 #This program illustrates an example of singly linked list
 #Linked lists do NOT support random access hence only sequential search can be carried out
 
+class Node(object):
+    def __init__(self, data, Next = None):
+        self.data = data
+        self.next = Next
+
+    def getData(self):
+        return self.data
+
+    def setData(self, data):
+        self.data = data
+
+    def getNext(self):
+        return self.next
+
+    def setNext(self, newNext):
+        self.next = newNext
+
 class LinkedList(object):
-    def __init__(self, head = None):
-        self.head = head
+    def __init__(self):
+        self.head = None
 
-    def insert(self, data):
-        newNode = Node(data)
-        newNode.setNext(self.head)
-        self.head = newNode
+    def isEmpty(self):
+        return self.head == None
+
+    def add(self, element):
+        temp = Node(element)
+        temp.setNext(self.head)
+        self.head = temp
 
     def size(self):
         current = self.head
         count = 0
-        while current:
-            count += 1
+        while current != None:
+            count = count + 1
             current = current.getNext()
+
         return count
 
-    def search(self, data):
+    def search(self,item):
         current = self.head
         found = False
-        while current and found != False:
-            if current.get_data() == data:
+        while current != None and not found:
+            if current.getData() == item:
                 found = True
             else:
                 current = current.getNext()
-        if current is None:
-            raise ValueError("Data not in list")
-        return current
 
-    def delete(self, data):
+        return found
+
+    def remove(self,item):
         current = self.head
         previous = None
         found = False
-        while current and found is False:
-            if current.getData() == data:
+        while not found:
+            if current.getData() == item:
                 found = True
             else:
                 previous = current
                 current = current.getNext()
-        if current is None:
-            raise ValueError("Data not in list")
-        if previous is None:
+
+        if previous == None:
             self.head = current.getNext()
         else:
             previous.setNext(current.getNext())
 
-class Node(object):
-    ''' Class for creating a singly linked list '''
-    def __init__(self, data, next = None):
-        ''' This constructor initilizes the node with the data and the next item in the list'''
-        self.data = data
-        self.next = next
+    def getAllData(self):
+        current = self.head
+        elements = []
+        while current:
+            elements.append(current.getData())
+            current = current.getNext()
 
-    def getData(self):
-        return self.data
+        return elements
 
-    def getNext(self):
-        return self.next
+if __name__ == '__main__':
+    myList = LinkedList()
 
-    def setNext(self, newNext):
-        self.next = newNext
+    print(myList.head)                  # None
 
-    def replace(self, targetItem, newItem):
-        probe = self
-        while probe != None and targetItem != probe.data:
-            probe = probe.next
-        if probe != None:
-            probe.data = newItem
-            print('Target Updated')
-            return True
-        else:
-            print('Target not found in the linked list')
-            return False
+    myList.add(12)
+    myList.add(2)
+    myList.add(22)
+    myList.add(32)
+    myList.add(42)
 
-if __name__ == '__main__':
-    #node1 = Node("A", "B")
-    #node2 = Node("B", "C")
-    #node3 = Node("C")
-    #print(node1.data,'=>', node1.next)
-    #print(node2.data,'=>', node2.next)
-    #print(node3.data,'=>', node3.next)
-
-    #node = None
-    #for i in range(6, 1, -1):
-    #    node = Node(i, node)
-
-    #print(node.data)
-    #node.search(4)
-
-    #node.replace(2, 5)
-    #print(node.data)
-
-    node = LinkedList(1)
-    print(node.head)
-    node.insert(2)
-    print(node.head)
-    print(node.size())
+    print(myList.size())                # 5
+
+    print(myList.search(93))            # False
+    print(myList.search(12))            # True
+
+    print(myList.getAllData())