Design Singly Linked List

Think we have to design Singly Linked List :

What should come into our mind ???????????

 Linked List will have value field and reference to next node field.

Structure Definition of a node in a Singly Linked List :

// Definition for singly Linked List 

public class SinglyListNode {

    int val;

    SinglyListNode next;

    SinglyListNode(int x){

         val = x;

      }

}

Initiate a new Linked List : Represent a linked list using the head node.

class MyLinkedList {

       private SinglyListNode head;

       public MyLinkedList(){

       head = null;

       }

}

Traverse the linked list to get element by index.

private SinglyListNode getNode(int index){

 SinglyListNode cur = head;

 for(int i =0 ; i < index && cur != null ; ++i){

 cur = cur.next;

 }

return cur;

}

//Function to return last element of the List.

private SinglyListNode getTail(){

SinglyListNode cur = head;

while(cur !=null && cur.next !=null){

cur = cur.next;

}

return cur;

}

// Function to return value of index-th node in the linked list.

private int get(int index){

SinglyListNode cur = head;

for(int i =0 ;i < index && cur != null ; ++i){

cur = cur.next;

}

return cur == null ? -1 : cur.val;

}

// Function to add a new Node.

// Here adding the node before the first element.

public void addAtHead (int val){

SinglyListNode cur = new SinglyListNode(val);

cur.next = head;

head = cur;

return;

}

// Here adding a node to the last element of the linked list.

public void addAtTail(int val){
SinglyListNode cur = new SinglyListNode(val);
if(head == null){
cur.next = head;
head = cur;
return;
}

SinglyLinkedNode dummy = head;
while(dummy.next !=null){
dummy = dummy.next;
}
dummy.next = cur;
}


// Add at particular index and the val.

public void addAtIndex(int val , int index){

SinglyListNode cur = new SinglyListNode(val);
if(index == 0){
cur.next = head;
head = cur;
return;
}

SinglyListNode prev = getNode(index-1);
if(prev == null){
return;
}

SinglyListNode next = prev.next;
cur.next = next;
prev.next = cur;

}


Delete a Node :

public void deleteIntIndex(int index){

SinglyListNode cur = getNode(index);
if(cur == null){
return;
}

SinglyListNode prev = getNode(index-1);
SinglyListNode next = cur.next;

if(prev != null){
prev.next = next;
} else {
head = next;
}
}