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Adding correction for Circular linked list #2598

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Merged
siriak merged 2 commits into from
Oct 16, 2021
Merged

Adding correction for Circular linked list #2598

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f9ad53a
Adding correction for Circular linked list
DEBADRIBASAK Oct 13, 2021
71c827f
Merge branch 'master' into debadri-hacktober-3
siriak Oct 16, 2021
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40 changes: 39 additions & 1 deletion DataStructures/Lists/CircleLinkedList.java
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Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,14 @@ private Node(E value, Node<E> next) {
private int size;
// this will point to dummy node;
private Node<E> head = null;
private Node<E> tail = null; // keeping a tail pointer to keep track of the end of list

// constructer for class.. here we will make a dummy node for circly linked list implementation
// with reduced error catching as our list will never be empty;
public CircleLinkedList() {
// creation of the dummy node
head = new Node<E>(null, head);
tail = head;
size = 0;
}

Expand All @@ -37,10 +39,43 @@ public void append(E value) {
throw new NullPointerException("Cannot add null element to the list");
}
// head.next points to the last element;
head.next = new Node<E>(value, head);
if (tail == null){
tail = new Node<E>(value, head);
head.next = tail;
}
else{
tail.next = new Node<E>(value, head);
tail = tail.next;
}
size++;
}

// utility function for teraversing the list
public String toString(){
Node p = head.next;
String s = "[ ";
while(p!=head){
s += p.value;
s += " , ";
p = p.next;
}
return s + " ]";
}

public static void main(String args[]){
CircleLinkedList cl = new CircleLinkedList<Integer>();
cl.append(12);
System.out.println(cl);
cl.append(23);
System.out.println(cl);
cl.append(34);
System.out.println(cl);
cl.append(56);
System.out.println(cl);
cl.remove(3);
System.out.println(cl);
}

public E remove(int pos) {
if (pos > size || pos < 0) {
// catching errors
Expand All @@ -58,6 +93,9 @@ public E remove(int pos) {
// the last element will be assigned to the head.
before.next = before.next.next;
// scrubbing
if(destroy == tail){
tail = before;
}
destroy = null;
size--;
return saved;
Expand Down