Question

Write a remove(E val) method for CircularlyLinkedList class
This method remove the first occurrence of the node that contains the val.

Answer 1

Method to remove first occurrence of node that contain val is provided below.

void remove(E val) {
   // If head node is null then the list is empty
if(headNode==NULL) {
printf("Empty list");
}
   // If the list is not empty
   // If the head node contain required val
if(headNode->val == val) {
     
   // If there is more than one node
if(headNode->link != headNode) {
       // Make the head node as current
curr = headNode;
         
       // Parse thrrough the list until we get the previous node of head node
while(curr->link!=headNode) {
curr = curr->link;
}

       // Update the curr node link to next node after head
curr->link = headNode->link;
         
       // Update head node
headNode = headNode->link;
}
       // If there is only one node
   else
   {
       // Make head node null
headNode = NULL;
}

}

// If the head node does not contain required val and there is only one node
else if(headNode->val != val && headNode->link == headNode) {
printf("Data not found");
}
   // Otherwise make the head node as curr node
curr = headNode;
  
   // Parse through the list until head node or required node found
while(curr->link != headNode && curr->val != val) {
   // Prev node denote the previous node of curr node
prev = curr;
curr = curr->link;
}
   // Check the curr node has required val
if(curr->val == val) {
   // Update the prev node link
prev->link = prev->link->link;
  
   // free the curr node
free(curr);
}
// Otherwise val not found
else
printf("Data not found");
}