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Update DoublyLinkedList.java #3

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148 changes: 111 additions & 37 deletions DoublyLinkedList.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand All @@ -97,54 +99,42 @@ public void insertAtHead(int value){
}
public void insertAt(int data , int position){


if(position < 0){
position = 0;
}
if(position > length){
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;
}




Expand All @@ -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();
Expand All @@ -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());
}

}