how to remove dulplicate elements from an unsorted linked list
// Java program to remove duplicates from unsorted
// linked list
class LinkedList {
static Node head;
static class Node {
int data;
Node next;
Node(int d) {
data = d;
next = null;
}
}
/* Function to remove duplicates from an
unsorted linked list */
void remove_duplicates() {
Node ptr1 = null, ptr2 = null, dup = null;
ptr1 = head;
/* Pick elements one by one */
while (ptr1.next != null) {
ptr2 = ptr1;
/* Compare the picked element with rest
of the elements */
while (ptr2.next != null) {
/* If duplicate then delete it */
if (ptr1.data == ptr2.next.data) {
/* sequence of steps is important here */
dup = ptr2.next;
ptr2.next = ptr2.next.next;
System.gc();
} else /* This is tricky */ {
ptr2 = ptr2.next;
}
}
ptr1 = ptr1.next;
}
}
void printList(Node node) {
while (node != null) {
System.out.print(node.data + " ");
node = node.next;
}
}
public static void main(String[] args) {
LinkedList list = new LinkedList();
list.head = new Node(10);
list.head.next = new Node(12);
list.head.next.next = new Node(11);
list.head.next.next.next = new Node(11);
list.head.next.next.next.next = new Node(12);
list.head.next.next.next.next.next = new Node(11);
list.head.next.next.next.next.next.next = new Node(10);
System.out.println("Linked List before removing duplicates : \n ");
list.printList(head);
list.remove_duplicates();
System.out.println("");
System.out.println("Linked List after removing duplicates : \n ");
list.printList(head);
}
}
// This code has been contributed by Mayank Jaiswal