solve linked lists exercise

Author: thmran

.vscode/launch.json

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+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Python: Current File",
+            "type": "python",
+            "request": "launch",
+            "program": "${file}",
+            "console": "integratedTerminal"
+        }
+    ]
+}

data_structures/3_LinkedList/PracticeDoubleLinkedList.py

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+class Node:
+    def __init__(self,data = None, next = None, prev = None):
+        self.data = data
+        self.next = next
+        self.prev = prev
+
+class DoublyLinkedList():
+    def __init__(self):
+        self.head = None
+
+    def printForward(self):
+        if self.head is None:
+            print("Emty doubly List")
+            return
+        
+        itr = self.head
+        forwardll = ""
+        while itr:
+            forwardll += str(itr.data) + "--->"
+            itr = itr.next
+        
+        print(forwardll)
+    
+    def printBackWard(self):
+        if self.lastNode() is None:
+            print("Empty doubly List")
+            return
+
+        backwardll= ""
+        itr =self.lastNode()
+        while itr:
+            backwardll += str(itr.data) + "-->"
+            itr = itr.prev
+
+        print("Reverse Linked List:",backwardll)
+
+    def lastNode(self):
+        itr = self.head
+        while itr.next:
+            itr = itr.next
+        return itr
+
+    def getLength(self):
+        count = 0
+        itr = self.head
+        while itr:
+            count += 1
+            itr = itr.next
+        return count
+
+    def insertLinkedList(self, dataList):
+        self.head = None
+        for data in dataList:
+            self.insertAtEnd(data)
+
+    def insertAtEnd(self, data):
+        if self.head is None:
+            self.head = Node(data,None,None)
+            return
+
+        itr = self.head
+
+        while itr.next:
+            itr= itr.next
+            
+        itr.next = Node(data,None,itr)
+
+    def inserAtBeginning(self,data):
+        if self.head is None:
+            node = Node(data,self.head,None)
+            self.head = Node
+        else:
+            node = Node(data,self.head,None)
+            self.head.prev = node
+            self.head = node
+
+    def insertAtIndex(self, index, value):
+        if index < 0 or index > self.getLength():
+            raise Exception("invalid index")
+        
+        if index == 0:
+            self.inserAtBeginning(value)
+            return
+
+        itr = self.head
+        count = 1
+        while itr:
+            if count == index:
+                node = Node(value,itr.next,itr)
+                if node.next:
+                    node.next.prev = node
+                itr.next = node
+                break
+
+            itr = itr.next
+            count += 1
+
+def main():
+    ll = DoublyLinkedList()
+    ll.insertLinkedList(["banana","mango","grapes","orange"])
+    # ll.printForward()
+    # print(ll.getLength())
+    # ll.printBackWard()
+    ll.insertAtEnd("figs")
+    # ll.printForward()
+    # ll.printBackWard()
+    ll.insertAtIndex(4,"kiwi")
+    ll.insertAtIndex(0,"jackfruit")
+    ll.insertAtIndex(6,"dates")
+    ll.printForward()
+    ll.printBackWard()
+
+if __name__ == "__main__":
+    main()

data_structures/3_LinkedList/PracticeLinked_list.py

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+import json
+
+class Node:
+    def __init__(self,data=None,next=None):
+        self.data = data
+        self.next = next
+    
+class linkedList:
+    def __init__(self):
+        self.head = None
+
+    def insertAtBeginning(self, data):
+        node = Node(data,self.head)
+        self.head = node
+
+    def insertAtEnd(self, data):
+        if self.head is None:
+            self.head = Node(data,None)
+            return
+
+        itr = self.head
+        while itr.next:
+            itr = itr.next
+        
+        itr.next = Node(data,None)
+    
+    def printLinkedList(self):
+        if self.head is None:
+            print("linked list is empty")
+            return
+
+        itr = self.head
+        llstr = ''
+        while itr:
+            llstr += str(itr.data) + "-->"
+            itr =itr.next
+        
+        print(llstr)
+
+    def inserValues(self, dataList):
+        self.head =None
+        for data in dataList:
+            self.insertAtEnd(data)
+
+    def getLength(self):
+        itr = self.head
+        count = 0
+        while itr:
+            count += 1
+            itr = itr.next
+        return count
+
+    def removeItem(self, index):
+        if index < 0 or index >= self.getLength():
+            raise Exception("invalid index")
+
+        if index == 0:
+            self.head = self.head.next
+            return
+        
+        count = 0
+        itr = self.head
+        while itr:
+            if count == index -1 :
+                itr.next = itr.next.next
+
+            itr = itr.next
+            count += 1
+
+    def insertAt(self, index, value):
+        if index < 0 or index >= self.getLength():
+            raise Exception("invalid index")
+
+        if index == 0:
+            self.insertAtBeginning(value)
+            return
+        
+        count = 0
+        itr = self.head
+        while itr:
+            if count == index -1 :
+                node = Node(value,itr.next)
+                itr.next = node
+                break
+
+            itr = itr.next
+            count += 1
+
+    def insertAfterValues(self, currentData, insertValue):
+        count = 0
+        itr = self.head
+        while itr:
+            if currentData == itr.data:
+                node = Node(insertValue,itr.next)
+                itr.next = node
+                break
+
+            itr = itr.next 
+            count += 1
+
+    def removeValue(self,value):
+        if self.head is None:
+            return
+        
+        if self.head.data == value:
+            self.head = self.head.next
+            return
+
+        count = 0 
+        itr = self.head
+        while itr.next:
+            if itr.next.data == value:
+                itr.next = itr.next.next
+            
+            itr = itr.next
+            count += 1
+
+def main():
+    ll = linkedList()
+    # print(ll.getLength())
+    # ll.inserValues(['tung','trang','erererer'])
+    # print(ll.getLength())
+    # ll.printLinkedList()
+    # ll.removeItem(0)
+    # ll.printLinkedList()
+    # ll.insertAt(1,"hot boi")
+    # ll.printLinkedList()
+    ll.inserValues(["banana","mango","grapes","orange"])
+    ll.printLinkedList()
+    ll.insertAfterValues("orange","apple") # insert apple after mango
+    ll.printLinkedList()
+    ll.removeValue("orange") # remove orange from linked list
+    ll.removeValue("banana") # remove orange from linked list
+    ll.printLinkedList()
+
+
+if __name__ == "__main__":
+    main()