From dcdb9a8b0894815ed9b75f18102d675a4bf9c2c3 Mon Sep 17 00:00:00 2001
From: RanchCoder <52583285+RanchCoder@users.noreply.github.com>
Date: Sun, 4 Oct 2020 18:02:43 +0530
Subject: [PATCH] Update DoublyLinkedList.java

completed the remove functions on Sunday 04-01-2020 18:02
---
 DoublyLinkedList.java | 148 +++++++++++++++++++++++++++++++-----------
 1 file changed, 111 insertions(+), 37 deletions(-)

diff --git a/DoublyLinkedList.java b/DoublyLinkedList.java
index 9dde543..6ad7a29 100644
--- a/DoublyLinkedList.java
+++ b/DoublyLinkedList.java
@@ -76,15 +76,17 @@ public int getLength(){
     public void insertAtHead(int value){
         DllNode node = new DllNode(value,null,null);
         
+        //if our list is null
         if(length == 0){
             head.setNext(node);
             node.setPrev(head);
             
             tail.setPrev(node);
             node.setNext(tail);
-            length += 1;
+            length++;
             return;
         }
+        //if we have more than one element in list.
         else{
         node.setNext(head.getNext());
         node.setPrev(head);
@@ -97,6 +99,7 @@ public void insertAtHead(int value){
     }
     public void insertAt(int data , int position){
         
+        
         if(position < 0){
             position = 0;
         }
@@ -104,47 +107,34 @@ public void insertAt(int data , int position){
             position = length;
         }
         
-        
-        DllNode node ,  temp = head;
-        
-        if(head == null){
-            head = new DllNode(data);
-            tail.setPrev(head);
-            head.setNext(tail);
-        }
-        
         //when want to insert at head
         if(position == 0){
-            
             insertAtHead(data);
-            
+            return;
         }
-        else if(position == length){
-            
-            insertAtTail(data);
-            
-        }    
-        else{
         
-        for(int i = 1 ; i <= position ; i++){
+        //when we want to insert at tail
+        if(position == length){
+            insertAtTail(data);
+            return;
+        }
+        DllNode node ,  temp = head.getNext();
+        for(int i = 1 ; i < position ; i++){
             
             temp = temp.getNext();
             
         }
-        
-        
-        
+        System.out.println("temp data : "  + temp.getData());
         //we have reached a position before now.
-       
         node = new DllNode(data,null,null);
         
         node.setNext(temp.getNext());
-        node.setPrev(temp);
-        
         temp.getNext().setPrev(node);
         temp.setNext(node);
+        
+        
         length += 1;
-        }
+        
         
         
         
@@ -165,18 +155,97 @@ public void insertAtTail(int data){
         }
         
     }
+    // removing the first element 
+    public int removeFirst(){
+        //if no element in the list
+        if(length == 0){
+            return Integer.MIN_VALUE;
+        }
+        DllNode temp = head.getNext();
+        head.setNext(temp.getNext());
+        temp.getNext().setPrev(head);
+        length -= 1;
+        return temp.getData();
+        
+    }
+    //removing last element
+    public int removeLast(){
+        //if no element in list
+        if(length == 0){
+            return Integer.MIN_VALUE;
+        }
+        DllNode temp = tail.getPrev();
+        tail.setPrev(temp.getPrev());
+        temp.getPrev().setNext(tail);
+        length -= 1;
+        return temp.getData();
+        
+    }
     
-    public int removeFirst(){return 0;}
-    public int removeLast(){return 0;}
-    public synchronized void removeMatched(DllNode node){}
+    
+    public synchronized void removeAtPosition(int position){
+        if(position < 0){
+            position = 0;
+        }
+        //if position greater than the no of elements starting from 0
+        if(position > length - 1){
+            position = length - 1;
+        }
+        // to remove first element
+        if(position == 0){
+            removeFirst();
+            return;
+        }
+        //to remove last element
+        if(position == (length - 1)){
+            removeLast();
+            return;
+        }
+        //else to remove in between element
+        DllNode temp = head.getNext();
+        for(int i = 1 ; i < position ; i++){
+            temp = temp.getNext();
+        }
+        
+        
+        
+        temp.setNext(temp.getNext().getNext());  // since we reach one element before actual position , we need to set the next of current node to 
+                                                 //next of actual position node , so we skip the actual position node and reach its next node.
+        temp.getNext().setPrev(temp);          // now setting prev of node after position node to point to node before position node.
+         length -= 1;
+         return;
+         
+    }
+    
+    
+    public synchronized void removeMatched(DllNode node){
+        
+        if(length == 0){
+            return;
+        }
+        DllNode temp = head.getNext();
+        int pos = 0;
+        while(pos < length){
+            if(node.equals(temp)){
+                temp.getPrev().setNext(temp.getNext());
+                temp.getNext().setPrev(temp.getPrev());
+                length -= 1;
+                
+            }
+            pos += 1;
+        }
+        
+        
+    }
     public String toString(){
         
         String result = "[";
         DllNode node = head.getNext();
         
         for(int i = 0 ; i < length ; i++){
+            System.out.println("Node data at " + i +" is " + node.getData());
             result += node.getData();
-           if( i != (length - 1)){
+           if(i < length - 1){
                result += ",";
            }
             node = node.getNext();
@@ -192,26 +261,31 @@ public static void main(String[] args){
         DoublyLinkedList dll = new DoublyLinkedList();
         dll.insertAtHead(5);
         System.out.println(dll.toString());
-        System.out.println("list Length " + dll.getLength());
     
         dll.insertAtHead(15);
         System.out.println(dll.toString());
-        System.out.println("list Length " + dll.getLength());
         
         dll.insertAtTail(25);
         System.out.println(dll.toString());
         
-        dll.insertAt(35,1);
+        
+        dll.removeAtPosition(2);
         System.out.println(dll.toString());
         
         
-        dll.insertAt(45,dll.getLength());
-        System.out.println(dll.toString());
         
         
+        // dll.removeFirst();
+        // System.out.println(dll.toString());
+        
+        
+        // dll.removeLast();
+        // System.out.println(dll.toString());
+        
+        
+        // dll.insertAt(35,1);
+        // System.out.println(dll.toString());
         
-        dll.insertAt(65,dll.getLength() - 1);
-        System.out.println(dll.toString());
     }
         
 }